It basically means:
Catch "SomeExceptionType" into the variable "e" with the promise that we won't assign a different exception to "e" during the processing of the exception.
Mostly this is overkill, as if I'm catching an exception into a temporary variable name (e only is valid for the exception handling block), I don't have to police myself so strictly as to not trust myself to assign a different (possibly created) exception to the same variable name.
That said, perhaps this block is heavily maintained by a team of different-minded individuals, and one just wanted to be VERY sure that e was the original captured exception.