svn: explicitly specify tunnel-user to properly map rhodecode username on svn commit via SSH backend

- fixes  #5608

rhodecode/apps/ssh_support/lib/backends/svn.py

@@ -67,9 +67,12 b' class SubversionTunnelWrapper(object):'
 
     def command(self):
         root = self.server.get_root_store()
+        username = self.server.user.username
+
         command = [
             self.server.svn_path, '-t',
             '--config-file', self.svn_conf_path,
+            '--tunnel-user', username,
             '-r', root]
         log.debug("Final CMD: %s", ' '.join(command))
         return command

rhodecode/apps/ssh_support/tests/test_server_svn.py

@@ -70,8 +70,10 b' class TestSubversionServer(object):'
     def test_command(self, svn_server):
         server = svn_server.create()
         expected_command = [
-            svn_server.svn_path, '-t', '--config-file',
-            server.tunnel.svn_conf_path, '-r', svn_server.root
+            svn_server.svn_path, '-t',
+            '--config-file', server.tunnel.svn_conf_path,
+            '--tunnel-user', svn_server.user.username,
+            '-r', svn_server.root
         ]
 
         assert expected_command == server.tunnel.command()