tests/test-merge8.out

log: fix missing diff output for hg log -p in sub directory

prep(ctx, fns) receives paths relative to repository root, not cwd.

updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
pulling from ../a
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
(run 'hg update' to get a working copy)
1 files updated, 0 files merged, 1 files removed, 0 files unresolved