Revert "Disable Python compilation cache during build"

[NikolajBjorner]

Reverts #7052

Nightly: manylinux build:

Traceback (most recent call last):
File "scripts/mk_make.py", line 18, in
mk_bindings(API_files)
File "/__w/1/s/scripts/mk_util.py", line 3073, in mk_bindings
cp_z3py_to_build()
File "/__w/1/s/scripts/mk_util.py", line 3001, in cp_z3py_to_build
pycache_prefix_before = sys.pycache_prefix
AttributeError: module 'sys' has no attribute 'pycache_prefix'

[NikolajBjorner]

This is the pipeline that fails:

• job: ManyLinuxBuild
  variables:
  python: "/opt/python/cp37-cp37m/bin/python"
  name: ManyLinux
  displayName: "ManyLinux build"
  pool:
  vmImage: "ubuntu-latest"
  container: "quay.io/pypa/manylinux2014_x86_64:latest"
  steps:
  • script: $(python) scripts/mk_unix_dist.py --nodotnet --nojava
  • script: git clone https://github.com/z3prover/z3test z3test
  • script: $(python) z3test/scripts/test_benchmarks.py build-dist/z3 z3test/regressions/smt2
  • script: cp dist/*.zip $(Build.ArtifactStagingDirectory)/
  • task: PublishPipelineArtifact@0
    inputs:
    artifactName: '$(name)Build'
    targetPath: $(Build.ArtifactStagingDirectory)

Are there updates to it (python3 vs python2?) that apply?
An unrelated update to python scripts led to a regression for pypi installations in the latest release.
A fix is being triaged (or I guess it works given recent feedback on unrelated pypi issues for Mac x64).
The takeaway is it created some disruption downstream.

[wintersteiger]

Oh, yes, this needs a fix for older Pythons.