This release includes all changes to the 2.1.x branch up to and including the 2.1.16 release.

Enhancements:
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* Raise errors prior to build if any run or test deps are unsatisfiable  #2102
* Add skeleton function for RPM packages, to be used for things like Xorg  #2109
* Improve test coverage of workdir removal  #2111 #2112
* Match variants in conda_build_config.yaml with dep names (implicit jinja2 version spec) #2124

Bug fixes:
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* fix reference to cc.subdir (it is just subdir)  #2015
* fix failing test when using filename_hashing=False (non-existent json file)  #2087
* fix dependencies specified to conda-convert not being added  #2090
* fix disable_pip removing packages even when they are explicit recipe deps #2129
* fix pin_compatible jinja2 function not respecting lower_bound as None correctly  #2138