strptime() inconsistency

[Ben Abbott]

I've noticed that behavior of strptime() is not consistent for me on MacOS X.

Running the MacOS X binary for 3.2.3 from OctaveForge

fmt = "%d-%b-%Y";
str = "17-Sep-1789";
[tm, nc] = strptime (str, fmt)

tm =
{
  usec = 0
  sec = 0
  min = 0
  hour = 0
  mday =  17
  mon =  8
  year =  89
  wday = 0
  yday =  259
  isdst = 0
  zone = JST
}

nc =  12

However, the 3.2.3 binary I built using gcc 4.4.2, I obtain the result below. 
When I build the current sources using gcc 4.2.1, I also see the result below.

tm =
{
  usec = 0
  sec = 0
  min = 0
  hour = 0
  mday =  17
  mon =  8
  year = 0
  wday = 0
  yday = 0
  isdst = 0
  zone = unknown
}

nc = 0

This problem only occurs for dates prior to 01-Jan-1900.

Does anyone have an idea what might be the cause of this inconsistent behavior?

Ben