[2.1.5] AutoUpdate WALA error on RHEL-6.8

[yuxisun1217]

Description of problem:
waagent fails to run the AutoUpdated WALA process.

Version-Release number of selected component (if applicable):
WALinuxAgent-2.1.5

RHEL Version: RHEL-6.8
Python Version: 2.6.6

How reproducible:
100%

Steps to Reproduce:

1. Prepare a RHEL7.3 VM on Azure East US location(ASM mode) with WALA-2.1.5 installed. Enable wala auto-update in the /etc/waagent.conf:

AutoUpdate.Enabled=y

AutoUpdate.GAFamily=Prod

Then restart waagent service

service waagent restart

2. Wait until the new WALA package is downloaded. Check waagent.log.

Actual results:
waagent can't run the new WALA version.
There's error logs in waagent.log:

2016/08/25 20:20:17.474136 INFO Instantiating Agent WALinuxAgent-2.1.6 from package
2016/08/25 20:20:17.476843 INFO Agent WALinuxAgent-2.1.6 error state: Last Failure: 0.0, Total Failures: 0, Fatal: False
2016/08/25 20:20:17.476980 INFO Ensuring Agent WALinuxAgent-2.1.6 is downloaded
2016/08/25 20:20:17.738310 INFO Agent WALinuxAgent-2.1.6 downloaded from https://rdfepirv2bl2prdstr01.blob.core.windows.net/7d89d439b79f4452950452399add2c90/Microsoft.OSTCLinuxAgent__Prod__2.1.6
2016/08/25 20:20:17.799473 INFO Agent WALinuxAgent-2.1.6 unpacked successfully to /var/lib/waagent/WALinuxAgent-2.1.6
2016/08/25 20:20:17.877585 INFO Agent WALinuxAgent-2.1.6 loaded manifest from /var/lib/waagent/WALinuxAgent-2.1.6/HandlerManifest.json
2016/08/25 20:20:17.962055 INFO Agent WALinuxAgent-2.1.6 error state: Last Failure: 0.0, Total Failures: 0, Fatal: False
2016/08/25 20:20:17.977174 INFO Agent WALinuxAgent-2.1.6 downloaded successfully
2016/08/25 20:20:18.021588 INFO Event: name=WALinuxAgent, op=Install, message=Agent WALinuxAgent-2.1.6 downloaded successfully
2016/08/25 20:20:18.102944 INFO Agent WALinuxAgent-2.1.5 discovered WALinuxAgent-2.1.6 as an update and will exit
2016/08/25 20:21:12.959822 INFO Agent WALinuxAgent-2.1.5 launched with command 'python -u /usr/sbin/waagent -run-exthandlers' is successfully running
2016/08/25 20:21:13.048011 INFO Event: name=WALinuxAgent, op=Enable, message=Agent WALinuxAgent-2.1.5 launched with command 'python -u /usr/sbin/waagent -run-exthandlers' is successfully running
2016/08/25 20:21:13.146289 INFO Instantiating Agent WALinuxAgent-2.1.6 from disk
2016/08/25 20:21:13.195095 INFO Agent WALinuxAgent-2.1.6 error state: Last Failure: 0.0, Total Failures: 0, Fatal: False
2016/08/25 20:21:13.230193 INFO Ensuring Agent WALinuxAgent-2.1.6 is downloaded
2016/08/25 20:21:13.235666 INFO Agent WALinuxAgent-2.1.6 was previously downloaded - skipping download
2016/08/25 20:21:13.242621 INFO Agent WALinuxAgent-2.1.6 loaded manifest from /var/lib/waagent/WALinuxAgent-2.1.6/HandlerManifest.json
2016/08/25 20:21:13.328814 INFO Determined Agent WALinuxAgent-2.1.6 to be the latest agent
2016/08/25 20:21:13.343555 WARNING Agent WALinuxAgent-2.1.6 launched with command 'python -u bin/WALinuxAgent-2.1.6-py2.7.egg -run-exthandlers' failed with exception: execv() argument 1 must be encoded string without NULL bytes, not str
2016/08/25 20:21:13.566290 ERROR Event: name=WALinuxAgent, op=Enable, message=Agent WALinuxAgent-2.1.6 launched with command 'python -u bin/WALinuxAgent-2.1.6-py2.7.egg -run-exthandlers' failed with exception: execv() argument 1 must be encoded string without NULL bytes, not str
2016/08/25 20:21:13.675956 WARNING Agent WALinuxAgent-2.1.6 is permanently blacklisted
2016/08/25 20:21:13.749416 INFO Installed Agent WALinuxAgent-2.1.5 is the most current agent
2016/08/25 20:21:13.756486 INFO Agent WALinuxAgent-2.1.5 launched with command 'python -u /usr/sbin/waagent -run-exthandlers'

\# cat /var/lib/waagent/WALinuxAgent-2.1.6/error.json
{"was_fatal": true, "failure_count": 1, "last_failure": 1472127673.6758201}

Additional info:

1. Only exists on RHEL-6. Doesn't exist on RHEL-7.
2. If install WALA-2.1.6 directly, there's no error log. Only exists during AutoUpdate.

[yuxisun1217]

The new package is named "WALinuxAgent-2.1.6-py2.7.egg". Does it menas that it doesn't support python 2.6.6?