convert_git: avoid returning two entries for the same file in getchanges
This could happen in merge changesets if the merged file was different
from both parents.
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
abort: Permission denied: test-ro-message/b/vehicle