On Fri, 19 Oct 2018, H. Hirzel wrote:

> Hi Bernard
>
> I think the explanation lies in the following
>
> Let us assume we have the following situation in the trunk
>
> A.
> update n
> update n-1
> update n-2
> update n-3
>
> Then an update n+1 is made:
>
> B.
> update n+1
> update n
> update n-1
> update n-2
> update n-3
>
> and _immediately_ after it is discovered (within a few hours) that
> update n+1 needs to be reverted and that is done so we have C
>
> C.
> update n+ 2 = revert of update n+1
> update n+1
> update n
> update n-1
> update n-2
> update n-3
>
> Then somebody detects this _BEFORE_ an update n+3 is made.
> And deletes
> update n+ 2 = revert of update n+1
> update n+1
>
>
> Then the situation is now
>
> D
> update n
> update n-1
> update n-2
> update n-3
>
> and this is indeed A.
> No history to keep track of. The argument is that if an issue is
> detected within a reasonable short time it does not need to be
> recorded as history.

Unfortunately that is not true if you had updated your image to B, but 
didn't update it to C in time.
When the versions are removed (D), your image will stay tainted with the 
faulty version after updating. The only way to fix it is to manually 
revert to the previous version if that's possible at all.
So, while D looks the same as A, D won't fix your image updated to B. 
You'll be stuck with the faulty version and merge conflicts in the future 
if you don't notice that.
Had the two versions not be removed, the update process would be able to 
fix your image "automagically".

Levente

>
> This was discussed a few months ago on the list.
>
> Cases where this happens are actually rare (about every 6 months) and
> the general recommendation is to discuss things in the inbox first.
>
> --Hannes
>
>
> On 10/19/18, Bernhard Pieber <bernhard at pieber.com> wrote:
>> Hi Chris,
>>
>> It seems that you are quite annoyed and I assure you it is not my intention
>> to annoy you any further. However, I would like to clarify one thing because
>> it might make it easier for me to see where you come from. I have always
>> thought that the moment something is pushed to trunk it becomes part of the
>> history. Therefore I thought moving to Treated should only happen from
>> Inbox. As you said "It never was history" you must mean somehing slightly
>> different by history, right? I wonder what exactly?
>>
>> Cheers,
>> Bernhard
>>
>>> Am 18.10.2018 um 02:43 schrieb Chris Muller <asqueaker at gmail.com>:
>>>
>>> On Wed, Oct 17, 2018 at 5:51 PM Bert Freudenberg <bert at freudenbergs.de>
>>> wrote:
>>> On Wed, Oct 17, 2018 at 3:00 PM Chris Muller <asqueaker at gmail.com> wrote:
>>> > the issue at stake here is the sanctity of the version history.
>>>
>>> "Sanctity."   If only you REALLY felt that way...    :(
>>>
>>> 🤔
>>>
>>> ...then you would want the history to be usable by reflecting meaningful
>>> changes, and not noise.
>>>
>>> It's not a raw tape of a tape-recorder, but our creation as a community
>>> which is meant to be _useful_ to future consumers.
>>>
>>>
>>> > It's untouchable. Think of it as immutable, append-only.
>>>
>>> Versions buried more than one or two deep are untouchable.  The top
>>> version(s) are not.  Reverting to a prior version IS a use-case.
>>> Deleting or moving a version IS a use-case.  There are UI commands to
>>> do them.
>>>
>>> Nope. Not in Trunk. Only trunk admins can move versions. Because it is a
>>> last-resort option when all else fails.
>>>
>>> Yes, it is a last resort.  I'm sure we can do what's necessary to avoid
>>> having to resort to it.
>>>
>>> The discussion is preserved in the mailing list, we don't need or want it
>>> in the trunk artifact.
>>>
>>> Removing a short-term in-and-out caused no harm.  Leaving it in does.
>>>
>>>
>>> > Unless some commit actually breaks the update stream or does some other
>>> > kind of major damage to users systems, it is always preferable to revert
>>> > that commit by a subsequent commit.
>>>
>>> You have a penchant for stating things as "facts" without offering any
>>> rationale whatsoever.  I could do something similar by only
>>> saying,"it's rarely preferable to revert a commit by a subsequent
>>> commit," with no basis.
>>>
>>> It's a commonly accepted practices in our field:
>>>
>>> "since so much work is local within your clone, you have a great deal of
>>> freedom to rewrite your history locally. However, once you push your work,
>>> it is a different story entirely, and you should consider pushed work as
>>> final unless you have good reason to change it. "
>>>
>>> Another "should" statement, and yes, sometimes there is good reason.
>>>
>>>
>>>
>>> > Patrick did that, and nobody was adversely affected.
>>>
>>> No!  We've been through this but, since you're Bert...   you're
>>> conflating what you think is a "miniscule adverse effect" with "no
>>> adverse effect".   In truth the  __breadth__  of the impact is not
>>> miniscule:
>>>
>>>   - *Every client of every user* is adversely affected.
>>>   - *Every dimension of the hardware* is affected (memory, storage,
>>> network).
>>>   - And software -- the usability of the code repository and ancestral
>>> model.
>>>   - *Every future user* and their hard drives, memorys, and networks
>>> will also be adversely affected.
>>>   - These adverse effects are _permanent_,
>>>             even though they were conjured committed in only minutes
>>> from a whimsy.
>>>
>>> Growing the universe by 0.1% is a big deal that advsersely affects
>>> everybody whether they realize it or not.
>>>
>>> It was only by admin'ing, that nobody will be adversely affected.
>>>
>>> Sorry, I did not understand that you are worried about the physical
>>> history size.
>>>
>>> Just because we don't need or want to enshrine 2K worth of "discussion" in
>>> the trunk artifact and add 2K*(that .mcz file + every future .mcz file) *
>>> (every copy of that file on a computer (package-cache, etc.) * (every
>>> computer using Squeak), + (every running image memory) + (network transit)
>>> + (cpu) etc. etc., doesn't mean I'm actively "worried" about something.
>>> It would be like me saying to you, "I did not understand that you are
>>> worried about performance".  You may not be while still not necessarily
>>> wanting to degrade something down when given a choice not to.
>>>
>>>
>>> > Our rules about caution, restraint, doubt etc are to prevent these
>>> > critical problems from occurring, not to keep the version history
>>> > "pretty".
>>>
>>> Stop mischaracterizing the reason for maintaining a quality ancestry
>>> and code repository.
>>>
>>> I did not get that, sorry again. I also do not agree with it. We should
>>> fix our tools, not change history.
>>>
>>> It never was history.
>>>
>>> What about the real-world cost?
>>>
>>> Is there a single real-world benefit?  You haven't mentioned a single
>>> compelling one, just "should".
>>>
>>>
>>> > Also, I agree with Levente that your "inbox first" rule is not actually
>>> > what we agreed upon. When we promote someone to core developer we trust
>>> > them enough to judge whether to put stuff into trunk directly or not.
>>>
>>> Of course.  That's why it says "Guidelines" not "Rules".  This was
>>> written to instill a conservative approach to committing.  It really
>>> is a good approach for something you consider immutable.
>>>
>>> As I said before, "hopefully it won't happen very often, but if it
>>> does..."  Rest assured, I don't enjoy being this "bad guy"...   :(
>>>
>>> In a community as small as ours I think it's more valuable to be proactive
>>> than conservative.
>>> That was the original vision of the trunk development process - removing
>>> the gatekeepers, empowering individual developers. I still think that's a
>>> fundamentally good idea.
>>>
>>> Right, but this has nothing to do with any of that.  The state of the
>>> trunk is still where you left it, and you are just as empowered as you
>>> always were.  Nothing changed, there was an obvious "oops", it never was
>>> "history", so it was moved to Treated.  We should honor the spirit of the
>>> New Community Development Model.  The ancestry is not a tape-recorder like
>>> in git culture.
>>>
>>>  - Chris
>>
>>
>>