Missing magic variables in custom rcextensions/__init__.py

[Robert Rauch]

Hi all,

I have recently started using a custom rcextensions package for
improving our integration of Kallithea with other services like Jenkins
and Redmine.

Today I noticed, that our Kallithea produced 'internal server errors'
when viewing the sourcecode of revisioned files via the webfrontend. The
logfiles showed, that Kallithea was raising exceptions of type

    AttributeError: 'module' object has no attribute 'EXTRA_LEXERS'

I worked around this problem by providing the *missing* line

    EXTRA_LEXERS = {}

in my custom rcextensions/__init__.py.

Is this the intended behaviour of Kallithea? From my perspective, as a
user/admin, this is really annoying. Why doesn't Kallithea fall back to
its default of `EXTRA_LEXERS = {}` if it is not defined elsewhere?

Besides that, I think the rcextensions API needs more documentation.

Regards, Robert