Update Mininet patch for 2022 apr (#464)

* Update the patch applied when installing Mininet

* Additional changes intended to be part of previous commit

* Specify a particular recent commit of Mininet to use

vm-ubuntu-20.04/Vagrantfile

@@ -18,7 +18,7 @@ Vagrant.configure(2) do |config|
     dev.vm.provision "shell", inline: "chmod 755 /home/vagrant/py3localpath.py"
     dev.vm.provision "file", source: "patches/disable-Wno-error-and-other-small-changes.diff", destination: "/home/vagrant/patches/disable-Wno-error-and-other-small-changes.diff"
     dev.vm.provision "file", source: "patches/behavioral-model-use-correct-libssl-pkg.patch", destination: "/home/vagrant/patches/behavioral-model-use-correct-libssl-pkg.patch"
-    dev.vm.provision "file", source: "patches/mininet-dont-install-python2.patch", destination: "/home/vagrant/patches/mininet-dont-install-python2.patch"
+    dev.vm.provision "file", source: "patches/mininet-dont-install-python2-2022-apr.patch", destination: "/home/vagrant/patches/mininet-dont-install-python2-2022-apr.patch"
     dev.vm.provision "file", source: "clean.sh", destination: "/home/vagrant/clean.sh"
     dev.vm.provision "shell", inline: "chmod 755 /home/vagrant/clean.sh"
     dev.vm.provision "shell", path: "root-dev-bootstrap.sh"
@@ -31,6 +31,7 @@ Vagrant.configure(2) do |config|
     release.vm.provider "virtualbox" do |v|
       v.name = "P4 Tutorial Release" + Time.now.strftime(" %Y-%m-%d")
     end
+    release.vm.provision "file", source: "patches/mininet-dont-install-python2-2022-apr.patch", destination: "/home/vagrant/patches/mininet-dont-install-python2-2022-apr.patch"
     release.vm.provision "shell", path: "root-release-bootstrap.sh"
     release.vm.provision "shell", path: "root-common-bootstrap.sh"
     release.vm.provision "shell", privileged: false, path: "user-common-bootstrap.sh"

vm-ubuntu-20.04/patches/mininet-dont-install-python2-2022-apr.patch

@@ -0,0 +1,36 @@
+diff --git a/util/install.sh b/util/install.sh
+index fd584b8..5886199 100755
+--- a/util/install.sh
++++ b/util/install.sh
+@@ -5,6 +5,7 @@
+ 
+ # Fail on error
+ set -e
++set -x
+ 
+ # Fail on unset var usage
+ set -o nounset
+@@ -175,9 +176,9 @@ function mn_deps {
+     else  # Debian/Ubuntu
+         pf=pyflakes
+         pep8=pep8
+-        # Starting around 20.04, installing pyflakes instead of pyflakes3
++        # Starting around 18.04, installing pyflakes instead of pyflakes3
+         # causes Python 2 to be installed, which is exactly NOT what we want.
+-        if [ "$DIST" = "Ubuntu" -a `expr $RELEASE '>=' 20.04` = "1" ]; then
++        if [ "$DIST" = "Ubuntu" -a `expr $RELEASE '>=' 18.04` = "1" ]; then
+                 pf=pyflakes3
+         fi
+         # Debian 11 "bullseye" renamed 
+@@ -189,9 +190,10 @@ function mn_deps {
+         fi
+ 
+         $install gcc make socat psmisc xterm ssh iperf telnet \
+-                 ethtool help2man $pf pylint $pep8 \
++                 ethtool help2man pylint3 \
+                  net-tools \
+                  ${PYPKG}-pexpect ${PYPKG}-tk
++        $install --no-install-recommends $pf $pep8
+         # Install pip
+         $install ${PYPKG}-pip || $install ${PYPKG}-pip-whl
+         if ! ${PYTHON} -m pip -V; then

vm-ubuntu-20.04/user-common-bootstrap.sh

@@ -4,10 +4,12 @@
 set -xe
 
 # --- Mininet --- #
+MININET_COMMIT="aa0176fce6fb718a03474f8719261b07b670d30d"  # 2022-Apr-02
 git clone https://github.com/mininet/mininet mininet
 cd mininet
+git checkout ${MININET_COMMIT}
 PATCH_DIR="${HOME}/patches"
-patch -p1 < "${PATCH_DIR}/mininet-dont-install-python2.patch" || echo "Errors while attempting to patch mininet, but continuing anyway ..."
+patch -p1 < "${PATCH_DIR}/mininet-dont-install-python2-2022-apr.patch" || echo "Errors while attempting to patch mininet, but continuing anyway ..."
 cd ..
 # TBD: Try without installing openvswitch, i.e. no '-v' option, to see
 # if everything still works well without it.