JavaMessageFormatPlaceable contains the following code (with boring parts of the regexp snipped):

regex = re.compile(r"""...[-0#.,E;%\u2030\u00a4']...""")

But the \u escape sequence is supported by the re module only since Python 3.3. In older Python versions this regexp is equivalent to:

r"""...[-0#.,E;%234au']..."

which is definitely not what you wanted.

This bug was found using pydiatra.