drush --quiet cron not quiet

[troubleshooter]

Just upgraded from 5 to 8.1.11. Am using the recommended cron command from drush docs on two separate machines for multiple sites. A blank line is output each time the cron job is run, causing an email to be sent. Did not have this issue with 5. I redirected the output to a log file and sure enough, a blank line is output each time. See attached file.
drush-cron.log.zip

[weitzman]

Please try to find what code is emitting the blank line.

[troubleshooter]

I did take a look but frankly, I know next to nothing about PHP so I had no clue what I was looking at. I did some testing and I can tell you that the blank line is also output when cron is run without the quiet flag.
Output is:
<blank line>
Cron run successful. [success]

I then ran drush cron in debug mode both with and without the --quiet flag. The only place a blank line appears is in the same spot in the output for both.

drush -d --uri=http://test1.example.org --quiet cron
Phar detected. Proceeding to drush_main().
Loading drushrc "/etc/drush/drushrc.php" into "system" scope. [0.01 sec, 3.36 MB] [bootstrap]
Loading drushrc "/root/.drush/drushrc.php" into "home.drush" scope. [0.01 sec, 3.37 MB] [bootstrap]
Cache HIT cid: 8.1.11-commandfiles-0-60954001ac342546c761d962804718d9 [0.01 sec, 3.4 MB] [debug]
<--BLANK LINE HERE
Bootstrap to phase 0. [0.09 sec, 7.75 MB] [bootstrap]

This is the output of the same command without --quiet

Phar detected. Proceeding to drush_main().
Loading drushrc "/etc/drush/drushrc.php" into "system" scope. [0.01 sec, 3.36 MB] [bootstrap]
Loading drushrc "/root/.drush/drushrc.php" into "home.drush" scope. [0.01 sec, 3.37 MB] [bootstrap]
Cache HIT cid: 8.1.11-commandfiles-0-60954001ac342546c761d962804718d9 [0.02 sec, 3.4 MB] [debug]
<--BLANK LINE HERE
Bootstrap to phase 0. [0.1 sec, 7.73 MB] [bootstrap]

I didn't include the entire output as there is no indication of any blank lines anywhere else.

Hope this helps.