grep: display correct user/revision for --all in reverse.
Also handle multiple occurrences of the same line by storing
linestates in an array instead of a dict, and using difflib
to compute the difference between linestates.
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding b
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding b