Use python3 pip module instead of pip binary

Focal only provides a pip3 binary, no pip3.8. Instead of working around
that with a symlink, use the module instead.

Add version information output for this variant.

Change-Id: I7af194ecc40e4d43c10ce067a661bb6ab4ca37d4
diff --git a/tools/install_pip.sh b/tools/install_pip.sh
index 5eb538c..517669e 100755
--- a/tools/install_pip.sh
+++ b/tools/install_pip.sh
@@ -5,7 +5,7 @@
 # Update pip and friends to a known common version
 
 # Assumptions:
-# - if USE_PYTHON3=True, PYTHON3_VERSION refers to a version already installed
+# - PYTHON3_VERSION refers to a version already installed
 
 set -o errexit
 
@@ -53,6 +53,8 @@
     else
         echo "pip: Not Installed"
     fi
+    # Show python3 module version
+    python${PYTHON3_VERSION} -m pip --version
 }
 
 
@@ -125,7 +127,14 @@
 # Show starting versions
 get_versions
 
-# Do pip
+if [[ -n $PYPI_ALTERNATIVE_URL ]]; then
+    configure_pypi_alternative_url
+fi
+
+# Just use system pkgs on Focal
+if [[ "$DISTRO" == focal ]]; then
+    exit 0
+fi
 
 # Eradicate any and all system packages
 
@@ -143,10 +152,6 @@
 
 install_get_pip
 
-if [[ -n $PYPI_ALTERNATIVE_URL ]]; then
-    configure_pypi_alternative_url
-fi
-
 set -x
 
 # Note setuptools is part of requirements.txt and we want to make sure