In the docstring of programToCommands, it says that:
> Each command is a two-tuple of commandname,arg-list
Previously the T2CharStringPen was passing command args as tuples instead
of lists to the specializeCommands function with option generalizeFirst=False,
which would only make a shallow copy of the input commands to modify them
in place. The problem is that it attempted to call list-only methods, leading
to errors like:
File "fontTools/cffLib/specializer.py", line 432, in specializeCommands
args.insert(pos, 0)
AttributeError: 'tuple' object has no attribute 'insert'
Since the expectation of the code here and elsewhere is that args is a
list, it makes sense that the T2 pen passes lists instead of tuples to the
specializeCommands function.
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