merge: remember rename copies and parents properly on commit record copies in dirstate even if rename was remote this lets us record it properly at commit teach checkfilemerge about copies, including merge cases pull old copy code out of commit extend rename-merge1 test to show file index

% init
% commit
adding base
% qnew mqbase
% qrefresh
% qdiff
diff -r 67e992f2c4f3 base
--- a/base
+++ b/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qdiff dirname
diff -r 67e992f2c4f3 base
--- a/base
+++ b/base
@@ -1,1 +1,1 @@ base
-base
+patched