Question

I’d like to enable SVNAutoversioning for one repository only. Would this work?

<Location /repos/>
  DAV svn
  SVNParentPath /path/to/repositories
</Location>

<Location /repos/specific_repo/>
  SVNAutoversioning on
</Location>

Answer 1

No.
The SVNAutoversioning directive is an apache directive valid for the whole Location directive
In your (erroneous) example you would have an new “Location” without any SVN configuration in it. There is no inheritation of the parameters from one location to another. Also: which location should apache choose for accessing SVN?`Both would be valid.

You have to move your repositories with autoversioning into another location:

<Location /repos/>
  DAV svn
  SVNParentPath /path/to/repositories
</Location>

<Location /repos_auto/>
  DAV svn
  SVNAutoversioning on
  SVNParentPath /path/to/auto_versioning_repositories
</Location>

Obviously this will break some of the checkout URLS which you have to repair with

svn switch --relocate  

for pre SVN 1.7, resp.

svn relocate

for svn 1.7 clients