WALinuxAgent: warning: %postun(WALinuxAgent-2.0.16-2.noarch) scriptlet failed, signal 15

I’m provisioning a CentOs box 7.x from the Azure images in the portal. On startup I wan to update yum packages + install Tomcat ( this is POC for customer ).

I’m using CustomScriptExtension to download and run this script containing:

#!/bin/bash          
# some stuff

# Taken from: https://github.com/Azure/azure-quickstart-templates/blob/875d139c16c9c023dce519e6dd48c707e3473346/torque-cluster/azuredeploy.sh
sed -i "s/Defaults\s\{1,\}requiretty/Defaults \!requiretty/g" /etc/sudoers
sudo -u serveradmin sh -c "mkdir /home/serveradmin/.ssh/;echo Host worker\* > /home/serveradmin/.ssh/config; echo StrictHostKeyChecking no >> /home/serveradmin/.ssh/config; echo UserKnownHostsFile=/dev/null >> /home/serveradmin/.ssh/config"
if ! [ -f /home/serveradmin/.ssh/id_rsa ]; then
    sudo -u serveradmin sh -c "ssh-keygen -f /home/serveradmin/.ssh/id_rsa -t rsa -N ''"
fi

sudo yum update -y > update_log.txt
sudo yum install tomcat -y > instal_log.txt

However - this fails always and we found the following in the execution in the .errout of the script execution:

Non-fatal POSTUN scriptlet failure in rpm package WALinuxAgent-2.0.16-2.noarch

File location: /var/lib/waagent/Microsoft.OSTCExtensions.CustomScriptForLinux-1.4.1.0/download/0/stderr

Checking the update_log.txt file shows the context of this error:

Loaded plugins: fastestmirror, langpacks
Determining fastest mirrors
Resolving Dependencies
--> Running transaction check
---> Package ModemManager-glib.x86_64 0:1.1.0-6.git20130913.el7 will be updated
---> Package ModemManager-glib.x86_64 0:1.1.0-8.git20130913.el7 will be an update
...
...
...
  Updating   : 1:iwl1000-firmware-39.31.5.1-43.el7.noarch               329/639 
  Updating   : iwl5150-firmware-8.24.2.2-43.el7.noarch                  330/639 
  Updating   : iwl135-firmware-18.168.6.1-43.el7.noarch                 331/639 
  Updating   : iwl3160-firmware-22.0.7.0-43.el7.noarch                  332/639 
  Updating   : iwl7260-firmware-22.0.7.0-43.el7.noarch                  333/639 
  Cleanup    : WALinuxAgent-2.0.16-2.noarch                             334/639 
warning: %postun(WALinuxAgent-2.0.16-2.noarch) scriptlet failed, signal 15

The yum updates work but stop as soon as this error occurs. Can you guys point me to a solution?