Optimize return value of util._matcher for common command line case
This will trigger every time somebody runs something like "hg diff"
or "hg status" without any arguments.
The important part here is returning util.always as the match function,
which is a much simpler (and faster) function than the usual return
value, and allows other code to just skip the filtering if it knows
all files will match.
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
pulling from ../source2
pulling from ../source1
requesting all changes
adding changesets
adding manifests
adding file changes
added 10 changesets with 10 changes to 1 files
(run 'hg update' to get a working copy)
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 11 changesets, 11 total revisions