>>> "{:\x00<5}".format(2)
'2 '
>>> "{:\x20<5}".format(2)
'2 '
>>> "{:\x01<5}".format(2)
'2\x01\x01\x01\x01'
>>> "{:\x00<5}".format(2) == "{:\x20<5}".format(2)
True
The docs say "If a valid align value is specified, it can be preceded by a fill
character that can be any character and defaults to a space if omitted," so I'm inclined to call this a good old fashioned bug.
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