shutil.copyfile is incomplete (truncated)

[Rob Schneider]

Using Python 2.7.2 on OSX, I have created a file in temp space, then use the function "shutil.copyfile(fn,loc+fname)" from "fn" to "loc+fname".

At the destination location, the file is truncated. About 10% of the file is lost.  Original file is unchanged.

I added calls to "statinfo" immediately after the copy, and all looks ok (correct file size).

filecmp.cmp(fn,loc+fname)
print "Statinfo    :"+fn+":\n", os.stat(fn)
print "Statinfo    :"+loc+fname+":\n", os.stat(loc+fname)

But when I look at the file in Finder, destination is smaller and even looking at the file (with text editor) file is truncated.

What could be causing this?