If plugin fails to load log the traceback

Signed-off-by: John Dennis <jdennis@redhat.com>

If plugin fails to load log the traceback

If a plugin fails to load due to some kind of error it would be nice
if the error log contained the traceback so you can examine what went
wrong rather than being left blind as to why it failed to load.

ipalib/plugable.py

@@ -582,7 +582,8 @@ class API(DictProxy):
                     'skipping plugin module %s: %s', fullname, e.reason
                 )
             except StandardError, e:
-                self.log.error('could not load plugin module %r', pyfile)
+                import traceback
+                self.log.error('could not load plugin module %r\n%s', pyfile, traceback.format_exc())
                 raise e
 
     def finalize(self):