Every 6 months or so we see very hard to diagnose issues around linecounts, including for example:

blame lines not equal to expected linecount

The linecount / blame code really needs a complete re-write, or at least some major refactoring to really understand the problems that we are hitting.

This should include at least:

• much better debugging / logging
• better handling of issues with the repository, eg. when linecounts differ
• fallbacks to SCMs