Following up on a private message - in v2, when you run

./pants binary <target>

today and any inputs have changed (even if only first-party code) the pex creation will today re-run pip to re-resolve the remote dependencies. This is a byproduct of pex building being completely hermetic, and therefore dependent only on its inputs. We are actively working on fixing this in two ways: 1) Add support for building a pex on top of an existing pex, so that there is one stable 3rdparty requirements pex, and we build the binary pex out of that. 2) Allow pants to use Pex's existing caching mechanism (by allowing this specific form of side-effect).