tests/test-pull-pull-corruption2.t

subrepo: use safehasattr instead of hasattr

Some of these instances could be rewritten as clever getattr(x, y,
default) ladders, but that felt like it impeded readability too much
to be worth the modest efficiency gain.

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 a third repo to pull both other repos into it

  $ hg init version2
  $ hg -R version2 pull source1 &
  $ sleep 1
  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)
  $ hg clone --pull -U version2 corrupted
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 10 changesets with 10 changes to 1 files
  $ wait
  $ hg -R corrupted verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 10 changesets, 10 total revisions
  $ hg -R version2 verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 10 changesets, 10 total revisions