[PATCH] hooks: print out more information when loading a python hook fails

[Simon Heimberg]

# HG changeset patch
# User Simon Heimberg <simohe at besonet.ch>
# Date 1341592623 -7200
# Node ID 2778422f1d45b2fc1dac3afc9e88d461e85681dd
# Parent  fba17a64fa4978bfea19222da5e64a18cfddeecd
hooks: print out more information when loading a python hook fails

When loading a python hook with file syntax fails, there is no information that
this happened while loading a hook. When the python file does not exist even the
file name is not printed. (Only that a file is missing.)

This patch adds this information and a test for loading a non existing file and
a directory not being a python module.