quiskstart.sh installs downgraded version of tripleo-quickstart-extras

[Sorin Sbarnea]

pip install decides to downgrade an editable module

**Expected behavior**
Installation should not touch a package that was already installed from source as editable while trying to install dependencies of other packages.

I do mention that there is dependent package that would ask for a specific version of this package.

**Output**

Full build output at https://ci.centos.org/job/tripleo-quickstart-gate-master-delorean-quick-basic/7276/consoleFull but I will show important lines below:
```
16:08:25 Found existing installation: tripleo-quickstart-extras 2.1.1.dev1087
16:08:26 Uninstalling tripleo-quickstart-extras-2.1.1.dev1087:
16:08:26 Successfully uninstalled tripleo-quickstart-extras-2.1.1.dev1087
16:08:26 Successfully installed ... tripleo-quickstart-extras-2.1.1.dev867 ...
```

tripleo-quickstart-extras 2.1.1.dev1087 is found but is uninstalled, version tripleo-quickstart-extras-2.1.1.dev867 being used instead, which obviously is not what we want, especially as this is the repository being tested.

I have the impression that this issue is related to this line: http://codesearch.openstack.org/?q=python%20setup.py%20install%20egg_info%20--egg-base&i=nope&files=&repos=

[wes hayutin (weshayutin)]

Please investigate, but I'm pretty sure this is jenkins not quickstart.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/608234

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sorin Sbarnea (<email address hidden>) on branch: master
Review: https://review.openstack.org/608234