rust-utils: move the `filesystem_now` function to a util
This is going to be useful for an upcoming `hg update` fastpath.
$ . "$TESTDIR/helpers-testrepo.sh"
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
$ ( \
> testrepohgenv; \
> "$PYTHON" $TESTDIR/run-tests.py --with-hg=$HGTEST_REAL_HG -j 1 \
> $HGTEST_RUN_TESTS_PURE test-hghaveaddon.t \
> )
installed Mercurial in * seconds (glob) (?)
running 1 tests using 1 parallel processes
.
# Ran 1 tests, 0 skipped, 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 <<NO_CHECK_EOF
> importing this file should cause syntax error
> NO_CHECK_EOF
$ hghave custom
failed to import hghaveaddon.py from '.': invalid syntax (hghaveaddon.py, line 1)
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