Provide checkbox to have source code checked out with git clone and no shortcuts, and a way to remove cache

I had started this dialog at https://answers.atlassian.com/questions/36602948/answers/37028709

In short, Bamboo does not seem to checkout source code for a repository the same way I do, via `git clone` and there may even be a cache of that repository sitting around on the bamboo Linux agent that is outdated, in regards to at least the list of branches.

Example, create a bamboo build plan such that it does not remove the workspace after the job is done.
Then `cd` to that workspace and run:
git branch -r | wc -l
to get the count of branches.
then run
git fetch --prune
which would delete locally, any branches that no longer exist on the remote stash repository.
then run
git branch -r | wc -l
to see if the number of branches has changed.

Now, as a human being, checkout a workspace on the same machine (or other machine) using the `git clone` syntax,
then run
git fetch --prune
git branch -r | wc -l

Are the number of branches in the 2 scenarios, similar or very different?