Created attachment 966217 [details]
patch to ensure that the $PKTMP file is not attempted to be sent by mail if the files is empty

Description of problem:

When setting MAILTO recipients in /etc/sysconfig/packagekit-background /etc/cron.daily/packagekit-background will only check for the return value from the pkcon command before trying to send email reports. In the case that the pkcon has not output any message(s) to the temporary file named by $PKTMP in the script, the mail command is invoked trying to send a null message body as a report. Anacron will also send a mail with the warning from the mail command, " 
Null message body; hope that's ok".

In short, if MAILTO is set in /etc/sysconfig/packagekit-background and if pkcon returns anything else but return value 5 (nothing useful done) and at the same time does not output any warnings or error messages, two unneccessary emails are sent. 

Version-Release number of selected component (if applicable):

PackageKit-cron-0.5.8-23.el6.x86_64

How reproducible:
Daily.

Steps to Reproduce:
1. Set MAILTO in /etc/sysconfig/packagekit-background
2. Wait
3. Two emails are sent, from /etc/cron.daily/packagekit-background and anacron. None of these carry any useful information.

Actual results:
Useless unneccessary emails are sent

Expected results:
Only email with useful info should be sent from /etc/cron.daily/packagekit-background.cron

Additional info:

patch to use bash built-in test -s to check if $PKTMP actually contains information:

--- /etc/cron.daily/packagekit-background.cron	2014-05-20 15:31:02.000000000 +0200
+++ /etc/cron.daily/packagekit-background.cron.fix	2014-12-09 13:13:48.067878542 +0100
@@ -36,13 +36,16 @@
 
 # this is when seomthing useful was done
 if [ $PKCON_RETVAL -ne 5 ]; then
+    # Do we actually have something to report? Is $PKTMP non-empty?
+    if [ -s $PKTMP ]; then 
 	# send email
 	if [ -n "$MAILTO" ]; then
-		mail -s "System updates available: $SYSTEMNAME" $MAILTO < $PKTMP
+	    mail -s "System updates available: $SYSTEMNAME" $MAILTO < $PKTMP
 	else
 		# default behavior is to use cron's internal mailing of output from cron-script
-		cat $PKTMP
+	    cat $PKTMP
 	fi
+    fi
 fi