When readline encounters some binary data (I'm not sure which character causes this) in a stream opened with popen3, it returns the empty string indicating end of file BEFORE the file is actually finished.  This causes programs to terminate early.  The exact same file as a local file opened in "r" mode does not have this behaviour.

The stream is created using:
strm1, strm2, strm3 = popen2.popen3("cvs log")
and the problem is that one of the cvs log messages I'm looking at has some garabage data in it - I think it has some unix end of line's, but I'm not sure exactly what causes this.

The work-around is to readline another time to see if it returns '' again - this allows it to continue reading successfully.
I can attach a portion of the file if that would help, or do an od -x on the section that causes the problem.