Merge ubuntu-release-upgrader:python-is-python2 into ubuntu-release-upgrader:ubuntu/master

[Dimitri John Ledkov]

quirks: install python-is-python2-but-deprecated if python-minimal was installed.

quirks: install python-is-python2-but-deprecated if python-minimal was installed.

[Dimitri John Ledkov (xnox)]

Tested in a chroot upgrades.

[Brian Murray (brian-murray)]

review: Approve

diff --git a/DistUpgrade/DistUpgradeQuirks.py b/DistUpgrade/DistUpgradeQuirks.py
index 0c8dd9d..24bd563 100644
--- a/DistUpgrade/DistUpgradeQuirks.py
+++ b/DistUpgrade/DistUpgradeQuirks.py
@@ -163,6 +163,7 @@ class DistUpgradeQuirks(object):
         """ run after calculating the dist-upgrade """
         logging.debug("running Quirks.PostDistUpgradeCache")
         self._install_linux_metapackage()
+        self._install_python_is_python2()
 
     # helpers
     def _get_pci_ids(self):
@@ -833,6 +834,20 @@ class DistUpgradeQuirks(object):
             reason = "linux metapackage may have been accidentally uninstalled"
             cache.mark_install(linux_metapackage, reason)
 
+    def _install_python_is_python2(self):
+        """
+        Ensure the python-is-python2 is installed if python-minimal
+        was installed.
+        """
+        old = 'python-minimal'
+        new = 'python-is-python2'
+        cache = self.controller.cache
+        if old in cache and cache[old].is_installed:
+            logging.info("installing %s because %s was installed" % (new, old))
+            reason = "%s was installed on the system" % old
+            if not cache.mark_install(new, reason):
+                logging.info("failed to install %s" % new)
+
     def ensure_recommends_are_installed_on_desktops(self):
         """ ensure that on a desktop install recommends are installed
             (LP: #759262)
diff --git a/debian/changelog b/debian/changelog
index 3d76f2c..7f002f5 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,11 @@
+ubuntu-release-upgrader (1:20.04.16) UNRELEASED; urgency=medium
+
+  * DistUpgrade/DistUpgradeQuirks.py: Install python-is-python2 if
+    python-minimal is installed. This preserves /usr/bin/python on
+    upgrades.
+
+ -- Dimitri John Ledkov <[e-mail]>  Wed, 25 Mar 2020 21:44:19 +0000
+
 ubuntu-release-upgrader (1:20.04.15) focal; urgency=medium
 
   * DistUpgrade/DistUpgradeCache.py: Update kernel and initrd size calculation