Conda

Bug Fixes
* fix 4309 ignore EXDEV error for directory renames (4392)
* fix 4393 by force-renaming certain backup files if the path already exists (4397)

Bug Fixes
* actually revert json output for leaky plan (4383)
* fix not raising on pre/post-link error (4382)
* fix find_commands and find_executable for symlinks (4387)

Bug Fixes
* fix 'Uncaught backoff with errno 41' warning on windows (4366)
* revert json output for leaky plan (4349)
* audit os.environ setting (4360)
* fix 4324 using old dist string instead of dist object (4361)
* fix 4351 infinite recursion via code in 4120 (4370)
* fix 4368 conda -h (4367)
* workaround for symlink race conditions on activate (4346)

Improvements
* add exception message for corrupt repodata (4315)

Bug Fixes
* fix package not being found in cache after download (4297)
* fix logic for Content-Length mismatch (4311, 4326)
* use unicode_escape after etag regex instead of utf-8 (4325)
* fix 4323 central condarc file being ignored (4327)
* fix 4316 a bug in deactivate (4316)
* pass target_prefix as env_prefix regardless of is_unlink (4332)
* pass positional argument 'context' to BasicClobberError (4335)

Non-User-Facing Changes
* additional package pinning tests (4317)

Improvements
* vendor url parsing from urllib3 (4289)

Bug Fixes
* fix some bugs in windows multi-user support (4277)
* fix problems with channels of type <unknown> (4290)
* include aliases for first command-line argument (4279)
* fix for multi-line FTP status codes (4276)

Non-User-Facing Changes
* make arch in IndexRecord a StringField instead of EnumField
* improve conda-build compatibility (4266)

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)