Sourcecode for 'TimeDelta_or_None' contains errors

This is for version 1.2.2 of MySQLdb
Given lack of documentation of the function, the second part of this bug is based on an assumption.

Two things seem to be rather wrong with the code around the times.TimeDelta_or_None function.

1) At line 63 there is a comparison of variable 'h' with 0, which determines whether to return the timedelta or an inverted timedelta. The bug lies in the fact that 'h' at that point is a string, and thus always compares larger than an integer.

2) This is based on the assumption that a timedelta string '-1:14:30' is the inverse of '1:14:30'. 12:00:00Z + '-1:14:30' results into 10:45:30Z according to this.

The problem is that the function in its current form creates a timedelta for negative 1 hour, and then positive 14 minutes 30 seconds, resulting in negative 45 minutes 30 seconds.

Below is the code I use in my own module that does what I suspect TimeDelta_or_None should do:

try:
hour, minute, second = string.split(':')
micro, second = math.modf(float(second))
timedelta = datetime.timedelta(
hours=abs(int(hour)), minutes=int(minute),
seconds=int(second), microseconds=int(micro * 1000000))
return (-1, 1)[int(hour) > 0] * timedelta
except:
return None