Fixed test-extdiff.
diff-like tools usually return 1 if differences are found.
Currently the extdiff returns 256, but that's a different topic
(consolidating return code handling in hg).
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
pushing to ../a
searching for changes
abort: unsynced remote changes!
(did you forget to sync? use push -f to force)
pulling from ../a
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)
pushing to ../a
searching for changes
abort: push creates new remote branches!
(did you forget to merge? use push -f to force)
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
pushing to ../a
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 1 changes to 1 files
adding foo
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
merging foo
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
pushing to ../c
searching for changes
abort: push creates new remote branches!
(did you forget to merge? use push -f to force)
pushing to ../c
searching for changes
no changes found
pushing to ../c
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files (+2 heads)
pushing to ../c
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (-1 heads)