Prepare sources in setup.py if c.tgz does not exist

[ichernev]

I think this change makes the project a bit more user friendly. I had to read the source to figure out I had to download zookeeper and run the generate script with .. before the tgz.

[hannosch]

Why do you think, you'd need to do this?

c.tgz is created as part of the release process, and present in the source distributions available on pypi. This process is described in source-release-instructions.txt

[ichernev]

Oh, sorry. I didn't know there was a prepackages version in pypi. I also did not read the source-release-instructions.txt. But if you include the patch it would work fine in a prepackaged format, and for those who download just the source it would also just work (no reading, no nothing).

I had to use an older version of zookeeper, so I had to manually package it. I though this would benefit others in the same situation. Its not a very common scenario though.

You can drop the patch if you think its not worth.

[jeffwidman]

These days PyPI is the preferred distribution source so this is no longer relevant.