Fix long-standing excessive file merges Since switching to the multihead approach, we've been creating excessive file-level merges where files are marked as merged with their ancestors. This explicitly checks at commit time whether the two parent versions are linearly related, and if so, reduces the file check-in to a non-merge. Then the file is compared against the remaining parent, and, if equal, skips check-in of that file (as it's not changed). Since we're not checking in all files that were different between versions, we no longer need to mark so many files for merge. This removes most of the 'm' state marking as well. Finally, it is possible to do a tree-level merge with no file-level changes. This will happen if one user changes file A and another changes file B. Thus, if we have have two parents, we allow commit to proceed even if there are no file-level changes.

--- a/tests/test-merge6.out	Sun Aug 21 16:51:50 2005 -0700
+++ b/tests/test-merge6.out	Sun Aug 21 21:59:55 2005 -0700
@@ -6,7 +6,7 @@
 added 1 changesets with 1 changes to 1 files
 (run 'hg update' to get a working copy)
 bar should remain deleted.
-6b70e9e451a5a33faad7bbebe627e46b937b7364 644 foo
+f405ac83a5611071d6b54dd5eb26943b1fdc4460 644 foo
 pulling from ../A2
 searching for changes
 adding changesets
@@ -15,4 +15,4 @@
 added 1 changesets with 0 changes to 0 files
 (run 'hg update' to get a working copy)
 bar should remain deleted.
-6b70e9e451a5a33faad7bbebe627e46b937b7364 644 foo
+f9b0e817f6a48de3564c6b2957687c5e7297c5a0 644 foo