Merge "Provide an option to force pip --upgrade"

doc/source/configuration.rst

@@ -247,6 +247,21 @@ A clean install every time
 
         RECLONE=yes
 
+Upgrade packages installed by pip
+---------------------------------
+
+    | *Default: ``PIP_UPGRADE=""``*
+    |  By default ``stack.sh`` only installs Python packages if no version
+       is currently installed or the current version does not match a specified
+       requirement. If ``PIP_UPGRADE`` is set to ``True`` then existing required
+       Python packages will be upgraded to the most recent version that
+       matches requirements.
+    |
+
+    ::
+
+        PIP_UPGRADE=True
+
 Swift
 -----
 

inc/python

@@ -54,17 +54,23 @@ function get_python_exec_prefix {
 
 # Wrapper for ``pip install`` to set cache and proxy environment variables
 # Uses globals ``INSTALL_TESTONLY_PACKAGES``, ``OFFLINE``, ``PIP_VIRTUAL_ENV``,
-# ``TRACK_DEPENDS``, ``*_proxy``
+# ``PIP_UPGRADE``, ``TRACK_DEPENDS``, ``*_proxy``
 # pip_install package [package ...]
 function pip_install {
     local xtrace=$(set +o | grep xtrace)
     set +o xtrace
+    local upgrade=""
     local offline=${OFFLINE:-False}
     if [[ "$offline" == "True" || -z "$@" ]]; then
         $xtrace
         return
     fi
 
+    PIP_UPGRADE=$(trueorfalse False PIP_UPGRADE)
+    if [[ "$PIP_UPGRADE" = "True" ]] ; then
+        upgrade="--upgrade"
+    fi
+
     if [[ -z "$os_PACKAGE" ]]; then
         GetOSVersion
     fi
@@ -98,7 +104,7 @@ function pip_install {
         https_proxy="${https_proxy:-}" \
         no_proxy="${no_proxy:-}" \
         PIP_FIND_LINKS=$PIP_FIND_LINKS \
-        $cmd_pip install \
+        $cmd_pip install $upgrade \
         $@
 
     # Also install test requirements
@@ -110,7 +116,7 @@ function pip_install {
             https_proxy=${https_proxy:-} \
             no_proxy=${no_proxy:-} \
             PIP_FIND_LINKS=$PIP_FIND_LINKS \
-            $cmd_pip install \
+            $cmd_pip install $upgrade \
             -r $test_req
     fi
 }