rust-revlog: fix RevlogEntry.data() for NULL_REVISION
Before this change, the pseudo-entry returned by `Revlog.get_entry` for
`NULL_REVISION` would trigger errors in application code using it.
For example, this fixes a crash spotted with changelog data
while implementing RHGitaly: `Changelog.data_for_rev(-1)` was already
returning the pseudo content as expected, e.g., for `hg log`, but
`Changelog.entry_for_rev(-1).data()` would still crash with
"corrupted revlog, hash check failed for revision -1". There is
an added test for this scenario.
#require test-repo execbit
$ . "$TESTDIR/helpers-testrepo.sh"
$ cd "`dirname "$TESTDIR"`"
look for python scripts without the execute bit
$ testrepohg files 'set:**.py and not exec() and grep(r"^#!.*?python")'
[1]
look for python scripts with execute bit but not shebang
$ testrepohg files 'set:**.py and exec() and not grep(r"^#!.*?python")'
[1]
look for shell scripts with execute bit but not shebang
$ testrepohg files 'set:**.sh and exec() and not grep(r"^#!.*(ba)?sh")'
[1]
look for non scripts with no shebang
$ testrepohg files 'set:exec() and not **.sh and not **.py and not grep(r"^#!")'
[1]