be helpful if we don't see name=value

I noticed an improvement we could still make.  I had been constructing my environment variables programmatically, and I had a situation where the values where coming out blank, so my cron files had something like

SOMETHING=

which makes cron throw and error and refuse to load the file, at least on debian squeeze. 

I added some logic to try to be helpful to the user.  What do you think?