This code:

# fmt: off
 #nospace
 #  twospaces
# fmt: on

is changed to:

# fmt: off
# nospace
#  twospaces
# fmt: on

I expected the lines betwen # fmt: off and # fmt: on to remain unchanged.

• Version: master (19.10b1.dev22+gbe49ac7)
• OS: Ubuntu Linux
• Python: 3.6.9

Playground (master)