Issue: The connection to a SVN repository will not be closed by the plugin

[iandrey77888]

Fixing an issue, when if you open a task with any defined Subversion configuration, opening a job settigns page will cause the connections opened by this action to hang indefinitely

We have our SVN repositry configured to only allow 10 connections from any given IP-address at a time, and we ran into an issue, when we would routinely ran out of those. After some code inspection (and general poking around), we discovered that any time one would open a job configuration page, the check of credentials would not close the connection opened to verify the credentials.
This issue is probably not noticeable for a lot of users, since probably any configuration has a buit-in timeout of hanged connections.
This a quick and dirty fix, made so as to be as least likely to break anything else in the refactoring process (the code base contains a method that seems to be doing the exact same thing at a glance while correclty closing connection)

What was done

Fixed method (hudson.scm.SubversionSCM.ModuleLocation.DescriptorImpl#checkCredentialsId) contains an added finally clause that closes the repo connection, if it is not null (mirror copy of the supposed clone method)

Testing

Only manual testing was done while opening a job setting page with a defined SVN repository configuration in it, as well as running this job. We will use this build of a plugin in our workflow for now.

[iandrey77888]

After some testing on our jenkins, I can confidently say that this fixed the issue