Spack Bugfixes

• Spec removed from an environment where not actually removed if --force was not given (#37877)
• Speed-up module file generation (#37739)
• Hotfix for a few recipes that treat CMake as a link dependency (#35816)
• Fix re-running stand-alone test a second time, which was getting a trailing spurious failure (#37840)
• Fixed reading JSON manifest on Cray, reporting non-concrete specs (#37909)
• Fixed a few bugs when generating Dockerfiles from Spack (#37766,#37769)
• Fixed a few long-standing bugs when generating module files (#36678,#38347,#38465,#38455)
• Fixed issues with building Python extensions using an external Python (#38186)
• Fixed compiler removal from command line (#38057)
• Show external status as [e] (#33792)
• Backported archspec fixes (#37793)
• Improved a few error messages (#37791)

Full Changelog: https://github.com/spack/spack/compare/v0.20.0...v0.20.1