replace usage of os.popen() with util.popen()
To make this possible, I added a mode parameter to both implementations of
util.popen(), defaulting to 'r' (as it does in the Python stdlib).
adding a
% check custom patch options are honored
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
updating working directory
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
applying ../a.diff
Using custom patch
nothing changed