subrepo, hghave: use "svn --version --quiet" to determine version number

svn --version --quiet is implemented since svn 0.14.1 (August 2002)
and prints just the version number, not the long output (21 lines)
of "svn --version".

Additionally I expect this output format to be more stable, at least
it is not changed with different translations.

mercurial/subrepo.py

@@ -674,8 +674,8 b' class svnsubrepo(abstractsubrepo):'
 
     @propertycache
     def _svnversion(self):
-        output, err = self._svncommand(['--version'], filename=None)
-        m = re.search(r'^svn,\s+version\s+(\d+)\.(\d+)', output)
+        output, err = self._svncommand(['--version', '--quiet'], filename=None)
+        m = re.search(r'^(\d+)\.(\d+)', output)
         if not m:
             raise util.Abort(_('cannot retrieve svn tool version'))
         return (int(m.group(1)), int(m.group(2)))

tests/hghave.py

@@ -152,7 +152,7 b' def has_docutils():'
         return False
 
 def getsvnversion():
-    m = matchoutput('svn --version 2>&1', r'^svn,\s+version\s+(\d+)\.(\d+)')
+    m = matchoutput('svn --version --quiet 2>&1', r'^(\d+)\.(\d+)')
     if not m:
         return (0, 0)
     return (int(m.group(1)), int(m.group(2)))