An small issue which I guess is to be found in
the implementation of the buffer interface
for zero-length arrays:

>>> a = array.array("c")
>>> r = re.compile("bla")
>>> r.match(a)
SystemError: error return without exception set

Armin, what do you think of the attached patch?
File Added: empty-array.diff

It seems to me that an empty array should be
equivalent to an empty string.  Accessing it as a
buffer should return a buffer of length 0, not
raise ValueError.

In all cases, the fix in _sre.c is sensible.

Fixed in versions 54662 and 54663.
Now returns a buffer of length zero other than NULL.