Unable to resolve variable in repository URL when creating branches

Problem Description
In some cases, variable is included as part of the repository. For example it would be like the following.

http://myGitserver/${bamboo.projectname}.git

This would work fine, if you use it for normal build. However, upon creating branches, this variable is not resolved correctly. There would be error when you create branch from Plan configuration, when it tried to detect the available branches. In the log, there would be following error message.

2014-04-03 22:32:57,560 INFO [http-bio-8085-exec-11] [RetryingTaskExecutor] Task 'Detecting branches Git' was unsuccessful. Run 1 / 2. Exception thrown when running task 'Detecting branches Git', with message: http://myGitserver/${bamboo.projectname}.git: cannot open git-upload-pack

Steps to replicate

1. Create a variable called projectname with the value myProject for example
2. Use that variable in the plan repository URL field like :

   http://myGitserver/${bamboo.projectname}.git
   

3. Then on the Plan configuration, navigate to Branches Tab , click on Create Branch , you will notice that it will try to scan for error and it will throw the following error