[PROTON-2087] [Python] Detection of tox caches failure instaead of trying again if not initially found

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: proton-c-0.29.0
• Component/s: build, python-binding
• Assignee: Andrew Stitcher
• Reporter: Andrew Stitcher
• Created: 12/Aug/19 16:53
• Updated: 19/Aug/19 10:49
• Resolved: 12/Aug/19 17:37

Description

The usual behaviour of CMake find_xxx is to cache when the xxx is found but to retry if on rerunning CMake if the xxx wasn't found previously.

The check_python_module() macro didn't do this.

Additionally it only checked that PYTHON_EXECUTABLE was defined and not that it has a useful value too. So it would have attempted to use python even if we'd looked for it and had not found it.