verify: report first bad changeset
- add linkrev and file arguments to err
- track lowest reported linkrev in err
- find linkrev in a couple cases
- sort linkrevs when reporting a bunch of errors against a file
- tidy up lots of messages
- make more robust against damaged indexes
- report first bad changeset if an error is encountered
assuming destination git-repo-hg
initializing destination git-repo-hg repository
scanning source...
sorting...
converting...
1 t1
0 t2