Fix test-notify for systems without or with a different version of diffstat.
Some diffstat versions say "1 file changed", others "1 files changed".
adding a
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
% push should push to default when default-push not set
pushing
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
% push should push to default-push when set
pushing
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files