email: add References field in the header
This hopefully helps clients get the threading right.
manifest: fix _search() corner-case
It failed when searching the empty string in the null revision.
Improved error message for log --follow
Mads Kiilerich notes that the existing message was unclear
when a nonexistent file was supplied.
import: add similarity option (
issue295)
mq: recover more gracefully from interrupted qrefresh (
issue1216)