tests/test-pull-pull-corruption.t

subrepos: prompt on conflicts on update with dirty subrepos

Consider a repository with a single subrepository. The changesets in
the main repository reference the subrepository changesets like this:

  m0 -> s0
  m1 -> s1
  m2 -> s2

Starting from a state (m1, s0), doing 'hg update m2' in the main
repository will yield a conflict: the subrepo is at revision s0 but
the target revision says it should be at revision s2.

Before this change, Mercurial would do (m1, s0) -> (m2, s2) and thus
ignore the conflict between the working copy and the target revision.

With this change, the user is prompted to resolve the conflict by
choosing which revision he wants. This is consistent with 'hg merge',
which also prompts the user when it detects conflicts in the merged
.hgsubstate files.

The prompt looks like this:

  $ hg update tip
   subrepository sources for my-subrepo differ
  use (l)ocal source (fc627a69481f) or (r)emote source (12a213df6fa9)?

Corrupt an hg repo with two pulls.
create one repo with a long history

  $ hg init source1
  $ cd source1
  $ touch foo
  $ hg add foo
  $ for i in 1 2 3 4 5 6 7 8 9 10; do
  >     echo $i >> foo
  >     hg ci -m $i
  > done
  $ cd ..

create one repo with a shorter history

  $ hg clone -r 0 source1 source2
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd source2
  $ echo a >> foo
  $ hg ci -m a
  $ cd ..

create a third repo to pull both other repos into it

  $ hg init corrupted
  $ cd corrupted

use a hook to make the second pull start while the first one is still running

  $ echo '[hooks]' >> .hg/hgrc
  $ echo 'prechangegroup = sleep 5' >> .hg/hgrc

start a pull...

  $ hg pull ../source1 &

... and start another pull before the first one has finished

  $ sleep 1
  $ hg pull ../source2 2>/dev/null
  pulling from ../source2
  pulling from ../source1
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 10 changesets with 10 changes to 1 files
  (run 'hg update' to get a working copy)
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)

see the result

  $ wait
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 11 changesets, 11 total revisions