There are two errors in the documentation of the file object's
read() method found at

http://www.python.org/doc/current/lib/bltin-file-objects.html#l2h-242

Suggested changes (unindented) are shown below interspersed
with the current text with insertions noted by a '+' in the
first column:

     Read at most size bytes from the file (less if the read
     hits EOF before obtaining size bytes). If the size
     argument is negative or omitted, read all data until EOF
     is reached.
     
+ Under some circumstances (e.g. system call aborted by
+ a signal) read() called with a negative or absent size
+ argument may return data before EOF is reached (even in
+ blocking mode).
     
     The bytes are returned as a string object. An empty string
     is returned when EOF is encountered immediately. (For
     certain files, like ttys, it makes sense to continue
     reading after an EOF is hit.)

The last sentence above (the parenthetical one) is false for
Linux/Unix.  Once you hit EOF on a tty, it will return EOF
forever until it's closed and re-opened.  If the above sentence
is true for other OSes, I suggest it be so qualified --
otherwise it should just be deleted.
     
     Note that this method may call the underlying C function
     fread() more than once in an effort to acquire as close to
     size bytes as possible. Also note that when in
     non-blocking mode, less data than what was requested may
     be returned, even if no size parameter was given.