Follow-up to r1875921: Add missing test decorator.

Skip build_repcache() test if read_rep_cache() is not supported
by Python-SQLite version.

* subversion/tests/cmdline/svnadmin_tests.py
  (build_repcache): Add missing SkipUnless decorator.

Patch by: Denis Kovalchuk <denis.kovalchuk@visualsvn.com>

Index: subversion/tests/cmdline/svnadmin_tests.py
===================================================================
--- subversion/tests/cmdline/svnadmin_tests.py	(revision 1875922)
+++ subversion/tests/cmdline/svnadmin_tests.py	(working copy)
@@ -4038,6 +4038,7 @@ PROPS-END
 
 @SkipUnless(svntest.main.is_fs_type_fsfs)
 @SkipUnless(svntest.main.fs_has_rep_sharing)
+@SkipUnless(svntest.main.python_sqlite_can_read_without_rowid)
 def build_repcache(sbox):
   "svnadmin build-repcache"