ruamel.yaml dependency on Python 3.8-dev should be maintainable or disabled

[jayvdb]

Travis job for 3.8-dev was removed in ec48af4

Following on from #274 , it is quite likely that there will be another breaking change Cpython 3.8, or in Cython on CPython 3.8, requiring ruamel.yaml to be updated otherwise it fails.

If we add dependency ruamel.yaml>=0.15.98;python_version == '3.8', the minreqs version is ruamel.yaml==0.15.98;python_version == '3.8', and that will fail before Python 3.8 is finally released.

Removing the MINREQ Python 3.8-dev job is one option. Currently the .travis template job matrix doesnt support customisation. The template has other problems too moremoban/pypi-mobans#95

Another approach is for the requirement of ruamel.yaml to be hg+https://bitbucket.org/ruamel/yaml#egg=ruamel.yaml;python_version == '3.8', so that the latest version is always used, preventing caching , but

1. this doesnt work in setup.py where setup_use_markers mode is enabled, at least with old setuptools, as the extra name should be ruamel.yaml and dependency_links used for URLs.
2. it also probably doesnt work in setup.py where setup_use_markers mode is not enabled, for similar reasons as above.

coala-mobans has some template voodoo to help with the above, but it will take time to get that across into pypi-mobans.

Another, possibly simpler approach, is for minreqs template to omit pins for 3.8. Then the builds should pass as soon as ruamel.yaml releases a new version, and usually he is quite quick in doing releases.

[chfw]

released in 0.5.0

[jayvdb]

This is a post-0.5.0 problem which still exists.

[chfw]

stale issue