[BUG] Exceptions thrown in regcomp.cpp seem to not propagate up to Cython (leads to SIGABRT)

[shwina]

Exceptions that are thrown in the C++ code in regcomp.cpp seem to not propagate all the way up to Python and lead to a SIGABRT. For example:

>>> import cudf
>>> s = cudf.Series(["a"])
>>> s.str.extract("{\}")
terminate called after throwing an instance of 'cudf::logic_error'
  what():  CUDF failure at:/cudf/cpp/src/strings/regex/regcomp.cpp:565: invalid regex pattern: nothing to repeat at position 0
fish: “python” terminated by signal SIGABRT (Abort)

Our bindings to the extract function are marked except +, which means that the C++ code generated by Cython will catch any C++ exceptions thrown by cudf::strings::extract and rethrow them as Python errors. For example, this all works as expected when the error is thrown from outside regcomp.cpp:

>>> s.str.extract("blah")
---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
...
...
RuntimeError: CUDF failure at: /cudf/cpp/src/strings/extract/extract.cu:98: Group indicators not found in regex pattern

cc: @davidwendt is there something internally within libcudf that may be preventing exceptions from regcomp.cpp from being propagated up to the Python caller?