Clean up some merge logic
- rename mode to branch_merge
- use explicit update mode
- use negative mtime for updates that set mtime
- expand some cryptic variable names
- elaborate merge dirstate comments
- remove redundant manifest lookup for non-merge case
- remove impossible merge case
- fix up test cases
#!/bin/sh
hg init a
cd a
echo a > foo
hg add foo
hg commit -m 1 -d "0 0"
rm foo
hg remove foo
hg commit -m 2 -d "0 0"
cd ..
hg clone a b