Work around pip installed pkgs on Rackspace image

The upstream rackspace image has a bunch of pip installed packages as
cloud-init was installed via pip due to a lack of available system
packages.  This can break further system package installs, such as
markdown, which fails with

---
 Error unpacking rpm package python-markdown-2.4.1-1.el7.noarch
  error: unpacking of archive failed on file
   /usr/lib/python2.7/site-packages/Markdown-2.4.1-py2.7.egg-info: cpio: rename
---

Because that is a directory for the pip-installed package, and a file
in the RPM

Remove all pip installed packages on rackspace images before we start
to work around this.  I have filed an upstream issue with Rackspace
(ticket-id 140804-ord-0000134) and the issue is being worked on.

Change-Id: Id12d175143ed3b8e024d057d65fa67505c08042a

Author: ianw

functions-common

@@ -466,6 +466,13 @@ function is_arch {
     [[ "$(uname -m)" == "$1" ]]
 }
 
+# Quick check for a rackspace host; n.b. rackspace provided images
+# have these Xen tools installed but a custom image may not.
+function is_rackspace {
+    [ -f /usr/bin/xenstore-ls ] && \
+        sudo /usr/bin/xenstore-ls vm-data | grep -q "Rackspace"
+}
+
 # Determine if current distribution is a Fedora-based distribution
 # (Fedora, RHEL, CentOS, etc).
 # is_fedora

stack.sh

@@ -216,6 +216,14 @@ if is_ubuntu; then
     echo 'APT::Acquire::Retries "20";' | sudo tee /etc/apt/apt.conf.d/80retry
 fi
 
+# upstream Rackspace centos7 images have an issue where cloud-init is
+# installed via pip because there were not official packages when the
+# image was created (fix in the works).  Remove all pip packages
+# before we do anything else
+if [[ $DISTRO = "rhel7" && is_rackspace ]]; then
+    (sudo pip freeze | xargs sudo pip uninstall -y) || true
+fi
+
 # Some distros need to add repos beyond the defaults provided by the vendor
 # to pick up required packages.