Fix six package on opensuse for pip 10

openSUE Leap 15.0 and 15.1 both provide python3-six version 1.11.0.
Since version 1.12.0 was released, pip>=10 recognizes the version
difference and tries to uninstall the distro-provided version and fails.
This change adds another hack to remove the egg-info file for the six
library so that pip can manage it directly. We also have to wait to
install os-testr until after the fixup has happened since trying to
install it triggers the issue.

Depends-on: https://review.opendev.org/715175

Change-Id: I4649abe06b5893a5251bfcdd4234abccde6ceda2
(cherry picked from commit 6eb2c5990d)

stack.sh

@@ -773,9 +773,6 @@ if [[ "$OFFLINE" != "True" ]]; then
     PYPI_ALTERNATIVE_URL=${PYPI_ALTERNATIVE_URL:-""} $TOP_DIR/tools/install_pip.sh
 fi
 
-# Install subunit for the subunit output stream
-pip_install -U os-testr
-
 TRACK_DEPENDS=${TRACK_DEPENDS:-False}
 
 # Install Python packages into a virtualenv so that we can track them
@@ -793,6 +790,9 @@ fi
 source $TOP_DIR/tools/fixup_stuff.sh
 fixup_all
 
+# Install subunit for the subunit output stream
+pip_install -U os-testr
+
 if [[ "$USE_SYSTEMD" == "True" ]]; then
     pip_install_gr systemd-python
     # the default rate limit of 1000 messages / 30 seconds is not

tools/fixup_stuff.sh

@@ -221,6 +221,15 @@ function fixup_suse {
     # See https://bugzilla.suse.com/show_bug.cgi?id=1154871
     # May be removed once a new opensuse-15 image is available in nodepool
     sudo zypper up -y p11-kit ca-certificates-mozilla
+
+    # Since pip10, pip will refuse to uninstall files from packages
+    # that were created with distutils (rather than more modern
+    # setuptools).  This is because it technically doesn't have a
+    # manifest of what to remove.  However, in most cases, simply
+    # overwriting works.  So this hacks around those packages that
+    # have been dragged in by some other system dependency
+    sudo rm -rf /usr/lib/python3.6/site-packages/ply-*.egg-info
+    sudo rm -rf /usr/lib/python3.6/site-packages/six-*.egg-info
 }
 
 # The version of pip(1.5.4) supported by python-virtualenv(1.11.4) has