convert: fix the RevisionSpec import in the bzr module
This import was failing (because its invalid) which was resulting in
the following tests failing with chg running:
- test-convert-bzr.t
- test-convert-bzr-directories.t
- test-convert-bzr-ghosts.t
- test-convert-bzr-treeroot.t
- test-convert-bzr-114.t
- test-convert-bzr-merges.t
This commit fixes the import which in turn fixes the tests.
Test Plan:
Ran the aforementioned tests with and without '--chg' option.
Differential Revision: https://phab.mercurial-scm.org/D936
$ hg init
$ $PYTHON -c 'open("a", "wb").write(b"confuse str.splitlines\nembedded\rnewline\n")'
$ hg ci -Ama -d '1 0'
adding a
$ echo clean diff >> a
$ hg ci -mb -d '2 0'
$ hg diff -r0 -r1
diff -r 107ba6f817b5 -r 310ce7989cdc a
--- a/a Thu Jan 01 00:00:01 1970 +0000
+++ b/a Thu Jan 01 00:00:02 1970 +0000
@@ -1,2 +1,3 @@
confuse str.splitlines
embedded\r (no-eol) (esc)
newline
+clean diff