(I'm not sure I quite understand your point about pip being a transitive dependency - it seems to me that if its listed as a requirement it should be added to the mirror regardless of why it's there - but I guess that's moot in light of what --force-reinstall does with caching).
Is the solution to add the --no-use-wheel and --force-reinstall flags to the 'upgrade_format' template ?
Good point about the caching.
(I'm not sure I quite understand your point about pip being a transitive dependency - it seems to me that if its listed as a requirement it should be added to the mirror regardless of why it's there - but I guess that's moot in light of what --force-reinstall does with caching).
Is the solution to add the --no-use-wheel and --force-reinstall flags to the 'upgrade_format' template ?