--no-clean not working on pip 7.x with vcs install

[derekstavis]

I have some build scripts which uses pip to install a package from a git repository. The build script installs to a prefix (kind of a virtualenv) and repository's content are used after the install to pick up additional files. With pip 6.x series the following lines does the trick:

    pip install --target=$SITE_PACKAGES \
                --install-option="--install-scripts=$PREFIX_DIR/bin" \
                --build="$BUILD_DIR" \
                --no-deps \
                --no-use-wheel \
                --upgrade \
                --exists-action=i \
                --ignore-installed \
                --no-clean \
                $FULL_REPOSITORY

The behavior of pip 6.x is right: It clones the repository specified by $FULL_REPOSITORY, run the setup.py install and then leave the repository in $BUILD_DIR.

The behavior of pip 7.x, which I see as misleading, is that it removes the repository after running setup.py install, no matter if --no-clean is used or not.

[piotr-dobrogost]

Could be related to issue #2779

[dstufft]

Closing as a duplicate of #2779.