convert: config option for git rename limit By default, Git applies rename and copy detection to 400 files. The diff.renamelimit config option and -l argument to diff commands can override this. As part of converting some repositories in the wild, I was hitting the default limit. Unfortunately, the warnings that Git prints in this scenario are swallowed because the process running functionality in common.py redirects stderr to /dev/null by default. This seems like a bug, but a bug for another day. This commit establishes a config option to send the rename limit through to `git diff-tree`. The added tests demonstrate a too-low rename limit doesn't result in copy metadata being recorded.