Relational databases exist for a reason. Every effort that starts with “I really want to use this tool so let me shove a use case into it” always ends in disaster. Git has a purpose, and building an information management system is not one of them.

To start, how are you going to run queries on this bug tracker? How are you going to make sure it stays up to date for everyone at the company with sub-second latency? How are you managing access control? How do you keep the size under control over time?