transaction: avoid ambiguity of file stat at restoring from backup
In some cases below, copying from backup is used to restore original
contents of a file, which is backuped via addfilegenerator(). If
copying keeps ctime, mtime and size of a file, restoring is
overlooked, and old contents cached before restoring isn't invalidated
as expected.
- failure of transaction (from '.hg/journal.backup.*')
- rollback of previous transaction (from '.hg/undo.backup.*')
To avoid ambiguity of file stat at restoring, this patch invokes
util.copyfile() with checkambig=True.
This patch is a part of "Exact Cache Validation Plan":
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
Testing that hghave does not crash when checking features
$ hghave --test-features 2>/dev/null
Testing hghave extensibility for third party tools
$ cat > hghaveaddon.py <<EOF
> import hghave
> @hghave.check("custom", "custom hghave feature")
> def has_custom():
> return True
> EOF
(invocation via run-tests.py)
$ cat > test-hghaveaddon.t <<EOF
> #require custom
> $ echo foo
> foo
> EOF
$ run-tests.py $HGTEST_RUN_TESTS_PURE test-hghaveaddon.t
.
# Ran 1 tests, 0 skipped, 0 warned, 0 failed.
(invocation via command line)
$ unset TESTDIR
$ hghave custom
(terminate with exit code 2 at failure of importing hghaveaddon.py)
$ rm hghaveaddon.*
$ cat > hghaveaddon.py <<EOF
> importing this file should cause syntax error
> EOF
$ hghave custom
failed to import hghaveaddon.py from '.': invalid syntax (hghaveaddon.py, line 1)
[2]