D6643: convert: add a config option to help doing identity hg->hg conversion

[mharbison72 (Matt Harbison)]

mharbison72 added a comment.


  In D6643#97250 <https://phab.mercurial-scm.org/D6643#97250>, @valentin.gatienbaron wrote:
  
  > In D6643#97247 <https://phab.mercurial-scm.org/D6643#97247>, @mharbison72 wrote:
  >
  >> I ran this on the repo that was giving me fits last summer, and it stayed consistent up until just after the point where there was an octopus fixup merge.  I suspect the logic in that part of convert is too loose (i.e. it should be dropping files in the fixup merge that were already in the first merge if there weren't changes in the 3rd branch), but wasn't able to write a simple test.  (The original repo was in bzr, converted to hg, and then I had to reconvert to lfs.)  I've been swamped at work, so I don't have time to dig into it.  But no sense in holding this up, as there doesn't seem to be a regression here.
  >
  > I didn't quite understand. Are you saying your convert call cause hashes to change after this octopus merge, but it's not caused by my change, i.e. hg behaves this way even before?
  
  Yes, it was a pre-existing issue.  It's the problem that I referenced here, which your patch got to without any of the hacking that I did:
  
    https://www.mercurial-scm.org/pipermail/mercurial-devel/2018-July/118896.html
  
  >> Do you think there are other hash preserving things that can be added?  (Not asking you to do that.)  Or should we save this config name for such functionality?  I don't have any better name ideas, and don't have a problem adding more to this config option.
  >
  > I don't plan on making more changes that impact hashes at least (other than more perhaps tweaking the changelog files list some more).
  > Changes to the choice of p1/p2 in manifestlog/filelogs revisions would cause spurious hash changes. Changes in this area don't seem that likely though.
  > But if such a change did happen, you'd probably want to preserve hashes regardless of the specific source of the hash change. And if not, more specialized options can be minted.
  
  Correct.  I just wanted to make sure that nobody has a problem with this config morphing into a general "try really hard to keep hashes" setting in the future, if other tweaks need to be made.

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  rHG Mercurial

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  https://phab.mercurial-scm.org/D6643

To: valentin.gatienbaron, #hg-reviewers, mharbison72
Cc: mharbison72, mjpieters, mercurial-devel