shutil.copytree() uses shutil.copyfile() to copy files recursively.
shutil.copyfile() opens the source file for reading, and the destination
file for writing, followed by a call to shutil.copyfileobj().

If the file happens to be a named pipe rather than a normal file,
opening for read blocks the copying function, since the Unix OS needs a
writer process to attach to the same named pipe before the open-for-read
succeeds.

Rather than opening the file for reading, the correct action would
probably be to simply create a new named pipe with the same name at the
destination.
Looking at the Python2.3 code, the same type of problem seem to exist
for other non-normal file-types other than symlinks (eg device files,
sockets, and possibly a few others).