[Patch] Replace deprecated check_metadata()
The 'check' command was introduced in distutils 2.7, and it was made a sub-command of 'sdist' in the same version. Distribute's 'sdist' has so far ignored sub-commands and relies on deprecated BBB code to invoke the check.
The proposed patch makes 'sdist' properly call sub-commands and invoke check_metadata() only if no 'check' command is present.
Patch 'sdist': [[https://bitbucket.org/stefanholek/distribute/changeset/479833f6eabc]]