hghave: add a check for the `xz` compression utility
This isn't install by default on Mac, which causes a test failure. The logic
for avoiding the command is a little goofy, but nested `#if` isn't supported,
and it still seems worth running the hg command to see if anything explodes.
With this, the py3 tests run (almost) cleanly on 10.14.6:
# Ran 835 tests, 58 skipped, 1 failed.
Alas, the mac-packaging test is skipped because it's slow. The failure here is
in test-releasenotes-merging.t, complaining about not being able to import the
`fuzzywuzzy` module. I have it installed on py3 (thus the test isn't skipped),
but not on py2. So there must be some unintended cross pollination here when
running `hg` commands.
Differential Revision: https://phab.mercurial-scm.org/D7374
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ hg update 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo This is file c1 > c
$ hg add c
$ hg commit -m "commit #2"
created new head
$ hg merge 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ rm b
$ echo This is file c22 > c
Test hg behaves when committing with a missing file added by a merge
$ hg commit -m "commit #3"
abort: cannot commit merge with missing files
[255]