This is a pattern that should be avoided. So far hypothesis is the only
package using it if I am correct, let's not add more. Instead, we should solve the underlying issue.
That is, we build, install and test within one derivation. That we should split up.
Doing this more will only result in trouble.
This reverts commit 49e0bbb333, reversing
changes made to 2f2a55496a.
The `buildPython*` function computes name from `pname` and `version`.
This change removes `name` attribute from all expressions in
`pkgs/development/python-modules`.
While at it, some other minor changes were made as well, such as
replacing `fetchurl` calls with `fetchPypi`.
