The backported versions support old and new pips more robustly without
depending on pip internals.

Recently (in version 8.1.2), pip changed their internals in a
non-backwards compatible way, breaking the Salt pip modules.
Salt used to depend on these internals, but has since been updated
to no longer depend on them as they have no compatibility guarantees.
We have been encountering issues where Salt is finding a new pip
version, even though the installed pip is old (6.1.1). To work around
this issue, backport updated modules that handle both old and new pips.