[IronPython] BUG? IOError: Could not find file

[HEMMI, Shigeru]

Hello, IronPython Team,

On my MAC OS X (Panther) + mono + IronPython, I encounterd a bug for
the program.

class TESTINGwrite(file):
    def __init__(self, fname):
        file.__init__(self,fname,"w",1)
    def writesomething(self):
        self.write("Hi there\n")

if __name__=='__main__':
    x = TESTINGwrite("testing_TMP.txt")
    x.writesomething()
    x.close()

In IronPython, this code generats errer(see below), while CPython runs properly.
I am guessing this is a bug.

$ ipy IOErrorCouldNoFindFile.py
Traceback (most recent call last):
  File IOErrorCouldNoFindFile, line unknown, in Initialize
  File mscorlib, line unknown, in .ctor
  File mscorlib, line unknown, in .ctor
IOError: Could not find file "testing_TMP.txt".

regards,