Comment 2 for bug 1781412

Here's the Traceback:

Traceback (most recent call last):
  File "./bionic", line 8, in <module>
    sys.exit(main())
  File "/tmp/u-r-u/DistUpgrade/DistUpgradeMain.py", line 238, in main
    if app.run():
  File "/tmp/u-r-u/DistUpgrade/DistUpgradeController.py", line 1949, in run
    return self.fullUpgrade()
  File "/tmp/u-r-u/DistUpgrade/DistUpgradeController.py", line 1926, in fullUpgrade
    self.doPostUpgrade()
  File "/tmp/u-r-u/DistUpgrade/DistUpgradeController.py", line 1336, in doPostUpgrade
    self.quirks.run("PostUpgrade")
  File "/tmp/u-r-u/DistUpgrade/DistUpgradeQuirks.py", line 113, in run
    func()
  File "/tmp/u-r-u/DistUpgrade/DistUpgradeQuirks.py", line 138, in bionicPostUpgrade
    self._replaceDebsWithSnaps()
  File "/tmp/u-r-u/DistUpgrade/DistUpgradeQuirks.py", line 543, in _replaceDebsWithSnaps
    if proc.returncode == 0:
UnboundLocalError: local variable 'proc' referenced before assignment