Improvements
* respect Cache-Control max-age header for repodata (4220)
* add 'local_repodata_ttl' configurability (4240)
* remove questionable "nothing to install" logic (4237)
* relax channel noarch requirement for 4.3; warn now, raise in future feature release (4238)
* add additional info to setup.py warning message (4258)
Bug Fixes
* remove features properly (4236)
* do not use `IFS` to find activate/deactivate scripts to source (4239)
* fix 4235 print message to stderr (4241)
* fix relative path to python in activate.bat (4242)
* fix args.channel references (4245, 4246)
* ensure cache_fn_url right pad (4255)
* fix 4256 subprocess calls must have env wrapped in str (4259)