[Buildbot-commits] [Buildbot] #438: Mercurial does not update to the right revision when building a tag from a named branch

[Buildbot]

#438: Mercurial does not update to the right revision when building a tag from a
named branch
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Reporter:  cdevienne  |       Owner:
    Type:  defect     |      Status:  reopened
Priority:  major      |   Milestone:  undecided
 Version:  0.8.5      |  Resolution:
Keywords:             |
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Comment (by marcusl):

 Dustin: It would seem so, for the causal observer. :)

 However, due to the (slightly bone-headed, IMO) way tags are handled in
 Mercurial, the info about the tag itself is not preserved when cloning
 with '--rev', so the tag-info will not exist in the clone, even though the
 top revision is the one that was tagged.

 Tags are handled by a .hgtags, which is version controlled too, and since
 the tags are created in that file in a revision made **after** the
 revision being tagged (

 Basically:

  * Revision A is created
  * Revision B adds tag X to revision A
  * If "clone --rev = X" is executed, the clone contains rev A, but not B,
 so it does not know about tag X, so "update X" fails, as do my scripts for
 detecting the current version  from vc tags)

 There are a few ways to tackle this:

  * Always clone everything (easy, but potentially wasteful if a very old
 tag is being checked out)
  * Detect the revision B where tag was made, clone that one (tricky to
 implement, but certainly possible. I've seen code for this on
 stackoverflow.com )
  * Add tag locally using "hg tag X --local" (potentially dangerous due to
 conflicts with later updates, unless tag is removed after build or clone
 is not re-used"

 This has been discussed in several places, and the root issue has not been
 fixed yet. There is some resistance to fixing this in the Mercurial dev
 team, obviously for a few good reasons, and maybe because no fully
 superior solution is available, yet.

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Ticket URL: <http://trac.buildbot.net/ticket/438#comment:6>
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