Revision 1838813

Let 'svnadmin recover' prune the rep-cache even if it is disabled.

Part of issue #4077: "FSFS recover should prune unborn revisions from
rep-cache.db".

Also add tests for both cases (enabled, disabled).

Pruning the rep-cache even if disabled was included as r1213716 in the
original fix for issue #4077, first released in Subversion 1.7.3, but was
reverted in r1367674 (issue #4214, recovery should not create rep-cache.db)
and so omitted from Subversion 1.8 and later series of releases.

* subversion/libsvn_fs_fs/recovery.c
  (recover_body): Prune the rep-cache no matter whether it's in use.

* subversion/tests/cmdline/svnadmin_tests.py
  (read_rep_cache,
   check_recover_prunes_rep_cache): New functions.
  (recover_prunes_rep_cache_when_enabled,
   recover_prunes_rep_cache_when_disabled): New tests.
  (test_list): Run them.