actionlib needs patch

[Tobias-Fischer]

• /actionlib/library.py", line 170, in _message_to_yaml: if type(msg) in [int, long, float, str, bool]: needs change to if type(msg) in [int, float, str, bool]:
• from cStringIO import StringIO needs change to from io import BytesIO

[wolfv]

I wonder if we should really try to patch melodic enough to work reasonably with python 3 or if we should just rebuild wiht python 2.7?
Or maybe we should have both versions available, at least, and say that py 3.6 is more experimental.

[Tobias-Fischer]

I think python3 with melodic would be one of the big selling points for conda with Ros. We might run into issues with the python2 build, too, especially as packages aren't built by default with python2 on conda forge anymore. But we certainly will run into more of those issues. Not sure what's the best way forward :(

[Tobias-Fischer]

This particular case could be patched with: ros/actionlib#169