* Fix gem pristine not accounting for user installed gems. Pull request
    #2914 by Luis Sagastume.
  * Refactor keyword argument test for Ruby 2.7. Pull request #2947 by
    SHIBATA Hiroshi.
  * Fix errors at frozen Gem::Version. Pull request #2949 by Nobuyoshi
    Nakada.
  * Remove taint usage on Ruby 2.7+. Pull request #2951 by Jeremy Evans.
  * Check Manifest.txt is up to date. Pull request #2953 by David Rodríguez.
  * Clarify symlink conditionals in tests. Pull request #2962 by David
    Rodríguez.
  * Update command line parsing to work under ps. Pull request #2966 by
    David Rodríguez.
  * Properly test `Gem::Specifications.stub_for`. Pull request #2970 by
    David Rodríguez.
  * Fix Gem::LOADED_SPECS_MUTEX handling for recursive locking. Pull request
    #2985 by MSP-Greg.