exceptions when rendering template need better debug output

[aspiers]

See #6 for an example TypeError failure with useless debug output.

I'm not sure there's any way to get better debug without using a different thread handling mechanism. AFAICS the TypeError comes from rendering the template but I don't think it gets decorated with the number of the offending line in the template, and the stack trace resulting from #20 is in the context of the re-raise by futures.Future, not within the thread where it was originally raised. ICBW though - need to investigate further ...

[aspiers]

Here's another example of a useless stack trace:

Failed plugin bugzilla:bnc:
Traceback (most recent call last):
  File "/home/adam/.GIT/3rd-party/rapport/rapport/report.py", line 93, in create_report
    results[plugin] = tmpl.render(future.result())
  File "/usr/lib/python2.7/site-packages/concurrent/futures/_base.py", line 397, in result
    return self.__get_result()
  File "/usr/lib/python2.7/site-packages/concurrent/futures/_base.py", line 356, in __get_result
    raise self._exception
ProtocolError: <ProtocolError for apibugzilla.novell.com/xmlrpc.cgi: 401 Authorization Required>

so it's not just TypeErrors.

[mvidner]

I was hit by this too:

Failed plugin bugzilla:bnc: global name 'url' is not defined!
Traceback (most recent call last):
  File "/home/mvidner/svn/rapport/rapport/report.py", line 91, in create_report
    results[plugin] = tmpl.render(future.result())
  File "/usr/lib/python2.7/site-packages/concurrent/futures/_base.py", line 397, in result
    return self.__get_result()
  File "/usr/lib/python2.7/site-packages/concurrent/futures/_base.py", line 356, in __get_result
    raise self._exception
NameError: global name 'url' is not defined

The original backtrace (er, "traceback") is lost which is apparently the fault of the futures library. I'll try to add an option to disable the threading and hope that will make the exceptions clearer.

[mvidner]

I have a very crude and dirty hack for this: mvidner@7f30228.

[aspiers]

This was fixed by 9366bfb from #38.