I am not aware of any means for cross-referencing projects to reflect commits in the manner you are describing:
link the issues of "project-A" to be linked to "project-B" code commits.
I will state the obvious:
- What are describing is maintaining a release branch "project-A"
- And a development branch as "project-B"
Even though perforce is not git, I have found the "perforce best practices" paper to be the best description of how to maintain release and development branch sanity. Go directly to page 4 and begin reading there.
As you fix bugs in your customer facing "project-A", which is maintained on a release branch, merge those changes to master as described in the reference document.
I am far less in favor of "git flow" but I might as well mention it.
Bottom line: You cannot get there from here. There is not a solution to your problem within the scope of any source control I have ever used to the best of my knowledge (subversion, ClearCase, perforce, git).
Since your customer facing project-A has priority (based on my reading of other comments) you will want to bring project-B into project-A's repo.
This will constitute its own challenge, and based on that, using git-flow might suit your needs as you would be bring project-B in as the develop branch.
The difficulty of doing so is dependent on:
- How much divergence there is between the 2 projects.
- How familiar you are with git itself.
However, the sooner you tackle the problem, the sooner to eliminate a major pain point for your team.