- remove unused `BuildEnvironment` parameter: `no_clean`
- move helper to install build requirement to the `BuildEnvironment` class
- simplify a little the 2 different code paths (with and without build isolation)
Offload more work to the underlying pip command used to install the
build requirements, so there's no need to duplicate code to handle
environment markers/extras. This is done by setting the correct options
from the finder passed in argument to `_install_build_reqs`.
* fix build environment handling when using PyPy
* do use the build environment for all build commands
* allow installing and building a wheel of a PEP 518 enabled
package without prior installation of setuptools and/or wheels
* fix check for minimum supported requirements for PEP 518 support:
- correctly handle complex requirements
- both setuptools and wheels are needed
Setup build environment before first invocation of setup.py and improve test to actually make check that build requirements are installed upon invocation.