Merge branch 'ao/diff-populate-filespec-lstat-errorpath-fix' into maint

After an error from lstat(), diff_populate_filespec() function
sometimes still went ahead and used invalid data in struct stat,
which has been fixed.

* ao/diff-populate-filespec-lstat-errorpath-fix:
diff: fix lstat() error handling in diff_populate_filespec()

diff --cc diff.c
Simple merge