If .pip files are pip-compile'd separately, they can have different
pinned versions.  Then when installed together, pip can't resolve the
difference.  Instead, pip-compile multiple .in files to produce one .pip
file that is installed.

This reverts commit 015e42af088e03c4c69068b191be9212d7808689.

I used this tweak to the Makefile to mostly just add hashes, though some
dependencies were also upgraded, not sure why...

@@ -74,7 +74,7 @@ metasmoke:

 .PHONY: upgrade

-PIP_COMPILE = pip-compile --upgrade --allow-unsafe
+PIP_COMPILE = pip-compile --allow-unsafe --generate-hashes
 upgrade: export CUSTOM_COMPILE_COMMAND=make upgrade
 upgrade: 				## Update the *.pip files with the latest packages satisfying *.in files.
 	pip install -q -r requirements/pip-tools.pip

Wrote this bug for pylint, because I shouldn't have to add a pragma:
https://github.com/PyCQA/pylint/issues/6592