Reading a File That is Being Written To From Phobos

[dsimcha]

It seems that Phobos won't allow opening a file that is being written to by
another program.  I understand that this is unsafe behavior.  However, for my
purposes, I don't care and want to do it anyhow.  (My purposes are that I have
a program periodically dumping data to a file and every once in a while I want
another program to just parse the results and print a summary to the screen).
 I usually receive a message like:

std.stream.OpenException: Cannot open or create file <filename>

This occurs even when I can open the file in vi, etc.  Is this a conscious
design decision?  If not, is it a legitimate bug?