hook: split config reading further

hook: split config reading further

We want an easy way to fetch the hook config with and without honoring
"trusted" so that we can compare the values. So we extract the part
retrieving raw hook data from the config to be able to call it twice
in the next patch.

--- a/mercurial/hook.py	Thu Apr 14 02:28:46 2016 -0700
+++ b/mercurial/hook.py	Thu Apr 14 17:03:49 2016 -0700
@@ -162,12 +162,18 @@
     return r
 
 def _allhooks(ui):
+    """return a list of (hook-id, cmd) pairs sorted by priority"""
+    hooks = _hookitems(ui)
+    return [(k, v) for p, o, k, v in sorted(hooks.values())]
+
+def _hookitems(ui):
+    """return all hooks items ready to be sorted"""
     hooks = {}
     for name, cmd in ui.configitems('hooks'):
         if not name.startswith('priority'):
             priority = ui.configint('hooks', 'priority.%s' % name, 0)
             hooks[name] = (-priority, len(hooks), name, cmd)
-    return [(k, v) for p, o, k, v in sorted(hooks.values())]
+    return hooks
 
 _redirect = False
 def redirect(state):