Previously we were writing a delete marker file which is checked in
InstallRequirement.remove_temporary_source which is only invoked if the
user did not pass --no-clean (and a PreviousBuildDirError was not
raised). Since our TempDirectory machinery now respects these conditions
we can just wrap our source directory in that instead of using this
ad-hoc mechanism for tracking our delete preference.
This will let us clean up a lot of dead code that only existed for this
use case.
Previously, an InvalidRequirement would raise a NameError while trying
to raise an InstallationError because `req` was not defined.
Discovered while working on #6402.
Some systems have /tmp symlinked which confuses custom builds, such as
numpy. This ensures that real path is passed and that such builds
resolve their paths correctly during build and install.
Added test for the change and also for the previous related fix: #707
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*This was migrated from pypa/pip#3079 to reparent it to the ``master``
branch. Please see original pull request for any previous discussion.*
