hooks: use python 2.4 compatible exception handling

mercurial/hook.py

@@ -65,9 +65,10 b' def _pythonhook(ui, repo, name, hname, f'
                                '("%s" is not callable)') %
                              (hname, funcname))
     try:
-        # redirect IO descriptors the the ui descriptors so hooks that write
-        # directly to these don't mess the command protocol when running through
-        # the command server
+        try:
+            # redirect IO descriptors the the ui descriptors so hooks
+            # that write directly to these don't mess up the command
+            # protocol when running through the command server
         old = sys.stdout, sys.stderr, sys.stdin
         sys.stdout, sys.stderr, sys.stdin = ui.fout, ui.ferr, ui.fin