Intermittent failures when using --parallel--safe-build with parallel builds

[lkollar]

When using --parallel--safe-build option in Jenkins as described in the documentation sometimes one of the builds fails when tox is generating the sdist.

It seems that the sdist is being generated in the source directory which is shared across the builds.

running sdist
running egg_info
writing <redacted>.egg-info/PKG-INFO
writing dependency_links to <redacted>.egg-info/dependency_links.txt
writing requirements to <redacted>.egg-info/requires.txt
writing top-level names to <redacted>.egg-info/top_level.txt
reading manifest file '<redacted>.egg-info/SOURCES.txt'
writing manifest file '<redacted>.egg-info/SOURCES.txt'
running check
warning: check: missing required meta-data: url

copying files to <redacted>-0.3.0...
copying setup.py -> <redacted>-0.3.0
copying <redacted>.egg-info/PKG-INFO -> <redacted>-0.3.0/<redacted>.egg-info
error: could not create '<redacted>-0.3.0/<redacted>.egg-info/PKG-INFO': No such file or directory

OS: RHEL 6.8 amd64
pip list output:

Package        Version
-------------- -------
<redacted>  0.3.0
pip            18.0
pluggy         0.7.1
py             1.6.0
setuptools     39.2.0
six            1.11.0
toml           0.9.6
tox            3.4.0
virtualenv     16.0.0

[gaborbernat]

Mangling with the dist/distshare folders turned out to be incorrect; as they may be other intermediate folders that can still conflict. The proper solution will be to hold a file lock onto the build env all throughout performing the build. We'll do this in the next release. Thanks for reporting!