I have had a few, but largely they were easy to resolve. One thing I dislike about about homebrew over apt (and similar) is that it requires a fairly unpolished workflow to do personal mods and patches on a package, while the apt tool-chain allows for this stuff in a fairly polished (if idiosyncratic) way.
I find it quite the contrary as it summons git power upon /usr/local. So the workflow is basically just editing live in /usr/local/Library/Formula ('brew create url' scaffolds in many cases, 'brew edit formula' gets you to an existing one), committing, and handling merges on pull (which is what 'brew update' does)
If you want to contribute back, fork on github and add your repo as a remote, then push and submit a pull request.
It's really different than apt (which it is normal as Debian packaging has a massively different scope) , but IMHO much, much simpler and efficient.
