Revision 1860958

In svnserve, consistently handle errors in opening a repository.

These errors are still logged and reported to the client, as they were
before, but now it is done in the same way as everywhere else. (The error
logging now happens higher up the call stack.)

For CVE-2019-0203.

* subversion/svnserve/serve.c
  After reporting an error to the client, don't log it explicitly here and
  then clear it; instead return it so the caller can do so.