upgrade: Remove packages removed on old container

Some packages may have been removed on the old container for example
replaces by full versions. Remove them before installing packages since
you can usually not have both full and normal versions installed
at the same time.

scripts/upgrade.py

@@ -107,8 +107,13 @@ class Container:
                 print("Installing %s" % packages)
                 self.execute(['opkg', 'install'] + packages)
 
-        def package_set(self):
-                old_list = self.opkg_list_installed().split('\n')
+        def opkg_remove(self, packages):
+                print("Removing %s" % packages)
+                self.execute(['opkg', 'remove'] + packages)
+
+        def _package_set_from_str(self, s):
+                print("_package_set_from_str ", type(s))
+                old_list = s.split('\n')
                 old_packages = []
                 i = 1
                 for l in old_list:
@@ -119,6 +124,12 @@ class Container:
                                 old_packages.append(name)
                 return frozenset(old_packages)
 
+        def package_set(self):
+                return self._package_set_from_str(self.opkg_list_installed())
+
+        def orig_package_set(self):
+                return self._package_set_from_str(self.container.files.get('/etc/openwrt_manifest').decode('ascii'))
+
 def usage(argv):
         print("Usage:", argv[0], "<old container> <new container> <image>")
         exit(1)
@@ -161,9 +172,18 @@ def main(argv):
                 print("Update package list")
                 new.opkg_update()
 
+        orig_set = old.orig_package_set()
         old_set = old.package_set()
         new_set = new.package_set()
-        add_packages = list(old_set.difference(new_set).difference(['iw']))
+        del_set = orig_set.difference(old_set)
+        del_packages = list(del_set)
+        add_packages = list(old_set.difference(new_set).difference(['iw']).difference(del_set))
+
+        if len(del_packages) > 0:
+                print("Remove", del_packages)
+                new.opkg_remove(del_packages)
+        else:
+                print("No packages uninstalled")
 
         if len(add_packages) > 0:
                 print("Install", add_packages)