Create branch: Re-select default branch for "Branch from" when switching repositories

The 'Create Branch' feature allows users to create a new branch from BitBucket Server. The user is first asked to select which repository to create the branch in. This defaults to the last viewed repository.

The Branch From field captures where the branch is being created from. For the repository which is selected by default, this field defaults to its default branch e.g. master. However, when you switch the repository to another one, the Branch From field is not updated to then select the new repository's default branch.

Steps to reproduce on stash.atlassian.com:

1. View the 'Bamboo' repository so it is the last viewed one
2. Go to a JIRA issue on JDOG e.g. JPA-1435
3. Click 'Create branch' to initiate the feature in BBS
4. The repository selected should be 'Bamboo'. The branch from field should be 'master'.
5. Change the repository to 'JIRA Cloud'.

Expected:

• The branch from field should now be 'master' as that is the default for that repository.

Actual:

• The branch from field is cleared.