functions-common: Don't reguess Python versions

We have already established the correct version of Python to use during
installation, either automatically or through user-provided information
(USE_PYTHON3, PYTHON3_VERSION). Don't do it again.

Change-Id: I7bdf2be9a885994bf2c437dd104048a1ff2f6666
Closes-Bug: #1744096
1 file changed