externalsToRevisionMappings entries not removed

In the build configuration, the Source Repository tab displays a list of Externals Paths & Revisions.

This is information is stored in the database column: BUILD_DEFINITION.XML_DEFINITION_DATA; in the following xpath: /configuration/repository/svn/externalsToRevisionMappings.

When the svn:externals on the repository changes, new entries are added to this list; but old entries are not removed. So the list ends up showing more externals than are actually used.
Luckily, the 'Detect changes in externals option' correctly detects only changes in the actual externals used, and not any of the superfluous entries.

You should be able to look at the Source Repository tab and see an accurate list of externals.

To replicate:

1) Configure a repository URL with the following svn:externals property:

TestA https://<path to some repository location>
TestB https://<path to some other repository location>

2) Create a build plan pointing at this URL. After saving, check the Source Repository tab (you should see "TestA" and "TestB" listed in the externals).

3) Reconfigure the URL with the following svn:externals property:

TestA https://<path to some repository location>
TestC https://<path to a third repository location>

4) Edit & resave the build plan, re-run the build etc.. The Source Repository tab will now list "TestA", "TestB" and "TestC" (even though TestB is not longer referenced anywhere).