Plan is disabled if the URL of Subversion/Git is wrong

Problem Description
If there's a variable of the URL of the subversion or git repository in Bamboo plan, and when you run customised and override the variable wrongly, the plan will be disabled after the build is unabled to run. This could cause issues if the developers don't have the permission to enable the plan, and it might cause bottleneck in the process. This issue could also be replicated if you put wrong url in the Source repository in Plan configuration.

This happens if the git branch name is wrong as well.

Steps to replicate

1. Navigate to Configure Plan
2. On the Source repository, choose Subversion or Git and put wrong URL
3. Add Source Code Checkout task
4. Run the build
5. Notice the build won't be able to run and the plan is disabled

Another step to replicate

1. Navigate to Configure Plan
2. On the Source repository, choose Subversion or Git and put URL and Bamboo variable at the end, make sure the default value is valid URL. For example.

   http://svnserver/Repo/svn/${bamboo.svnbranchname}
   

3. Run Customised the plan and override the variable with wrong value
4. Notice the build won't be able to run and the plan is disabled