Why Integrate SCM With Bug-tracking?

SCM systems maintain software changes. Bug-tracking systems maintain lists of software enhancements and defects. By examining a log of software changes, it is uncertain why the changes occurred. By examining a log of defect reports, it is uncertain what changed in software in response to the defects.

Integration of SCM with bug-tracking ties the reason why a feature/defect was developed/fixed with what software changes occurred in the SCM system to accomplish this.