Fix cold cache diff performance cold cache diff performance has regressed in two ways. localrepo.changes has optimizations for diffing against the working dir parent that expect node1 to be None. commands.revpair() usage means that commands.dodiff() never sends node1 == None. This is fixed in localrepo.changes by checking against the dirstate parents. In the non-dirstate parents case, localrepo.changes does a loop comparing files without first sorting the file names, leading to random access across the disk.

requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions