Revert "Do not use pip 10 or higher"

This reverts commit f99d1771ba.

Added workarounds that might want to get split into their own patch
before merging:

- Don't install python-psutil
- Don't run peakmem_tracker

Change-Id: If4fb16555e15082a4d97cffdf3cfa608a682997d

.zuul.yaml

@@ -320,14 +320,12 @@
         dstat: true
         etcd3: true
         mysql: true
-        peakmem_tracker: true
         rabbit: true
     group-vars:
       subnode:
         devstack_services:
           # Shared services
           dstat: true
-          peakmem_tracker: true
         devstack_localrc:
           # Multinode specific settings
           HOST_IP: "{{ hostvars[inventory_hostname]['nodepool']['private_ipv4'] }}"
@@ -394,7 +392,6 @@
         dstat: true
         etcd3: true
         mysql: true
-        peakmem_tracker: true
         rabbit: true
         tls-proxy: true
         # Keystone services
@@ -450,7 +447,6 @@
           # This list replaces the test-matrix.
           # Shared services
           dstat: true
-          peakmem_tracker: true
           tls-proxy: true
           # Nova services
           n-cpu: true

files/debs/dstat

@@ -1,2 +1 @@
 dstat
-python-psutil

files/rpms-suse/dstat

@@ -1,2 +1 @@
 dstat
-python-psutil

files/rpms/dstat

@@ -1,3 +1,2 @@
 dstat # not:f29
 pcp-system-tools # dist:f29
-python-psutil

tools/cap-pip.txt

@@ -1 +0,0 @@
-pip!=8,<10

tools/install_pip.sh

@@ -89,9 +89,9 @@ function install_get_pip {
             die $LINENO "Download of get-pip.py failed"
         touch $LOCAL_PIP.downloaded
     fi
-    sudo -H -E python $LOCAL_PIP -c $TOOLS_DIR/cap-pip.txt
-    if python3_enabled; then
-        sudo -H -E python${PYTHON3_VERSION} $LOCAL_PIP -c $TOOLS_DIR/cap-pip.txt
+    sudo -H -E python${PYTHON3_VERSION} $LOCAL_PIP
+    if ! python3_enabled; then
+        sudo -H -E python $LOCAL_PIP
     fi
 }