Persistent variables containing underscores are not properly detected sometimes

[m-from-space]

Here is an example of the issue:

default persistent.VARIABLE = True
default persistent.SOME_VARIABLE = True
default persistent.SOME_OTHER_VARIABLE = True

label start:

    $ v = persistent.VARIABLE

    $ v = persistent.SOME_VARIABLE

    $ v = persistent.SOME_OTHER_VARIABLE

    $ v = (persistent.SOME_OTHER_VARIABLE)

    $ persistent.SOME_OTHER_VARIABLE = False

    $ persistent.NON_EXISTENT = False

    return