run-tests.py: pass -L/--label to simplemerge
This should give us conflict markers that don't change from one run
to another.
Remove some sed's/egrep's from some tests.
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