Error occurred during build: Command 01_mount failed

Tried this, set the vpc and subnet, but got this error, not sure why yet...

```
2020-05-20 16:51:17,029 [INFO] -----------------------Starting build-----------------------
2020-05-20 16:51:17,035 [INFO] Running configSets: _OnInstanceBoot
2020-05-20 16:51:17,038 [INFO] Running configSet _OnInstanceBoot
2020-05-20 16:51:17,041 [INFO] Running config AWSEBBaseConfig
2020-05-20 16:51:17,165 [INFO] Command clearbackupfiles succeeded
2020-05-20 16:51:17,169 [INFO] Running config AWSEBCfnHupEndpointOverride
2020-05-20 16:51:17,173 [INFO] Command clearbackupfiles succeeded
2020-05-20 16:51:17,174 [INFO] ConfigSets completed
2020-05-20 16:51:17,174 [INFO] -----------------------Build complete-----------------------
2020-05-20 16:52:07,557 [INFO] -----------------------Starting build-----------------------
2020-05-20 16:52:07,564 [INFO] Running configSets: Infra-EmbeddedPreBuild
2020-05-20 16:52:07,567 [INFO] Running configSet Infra-EmbeddedPreBuild
2020-05-20 16:52:07,569 [INFO] Running config prebuild_0_spectre_blog
2020-05-20 16:52:11,566 [ERROR] Command 01_mount (/tmp/mount-efs.sh) failed
2020-05-20 16:52:11,566 [ERROR] Error encountered during build of prebuild_0_spectre_blog: Command 01_mount failed
Traceback (most recent call last):
File "/usr/lib/python2.7/site-packages/cfnbootstrap/construction.py", line 542, in run_config
CloudFormationCarpenter(config, self._auth_config).build(worklog)
File "/usr/lib/python2.7/site-packages/cfnbootstrap/construction.py", line 260, in build
changes['commands'] = CommandTool().apply(self._config.commands)
File "/usr/lib/python2.7/site-packages/cfnbootstrap/command_tool.py", line 117, in apply
raise ToolError(u"Command %s failed" % name)
ToolError: Command 01_mount failed
2020-05-20 16:52:11,567 [ERROR] -----------------------BUILD FAILED!------------------------
2020-05-20 16:52:11,567 [ERROR] Unhandled exception during build: Command 01_mount failed
Traceback (most recent call last):
File "/opt/aws/bin/cfn-init", line 171, in
worklog.build(metadata, configSets)
File "/usr/lib/python2.7/site-packages/cfnbootstrap/construction.py", line 129, in build
Contractor(metadata).build(configSets, self)
File "/usr/lib/python2.7/site-packages/cfnbootstrap/construction.py", line 530, in build
self.run_config(config, worklog)
File "/usr/lib/python2.7/site-packages/cfnbootstrap/construction.py", line 542, in run_config
CloudFormationCarpenter(config, self._auth_config).build(worklog)
File "/usr/lib/python2.7/site-packages/cfnbootstrap/construction.py", line 260, in build
changes['commands'] = CommandTool().apply(self._config.commands)
File "/usr/lib/python2.7/site-packages/cfnbootstrap/command_tool.py", line 117, in apply
raise ToolError(u"Command %s failed" % name)
ToolError: Command 01_mount failed

```

Start with the build log and the /tmp/mount-efs.sh command invoked by 01_mount. Compare the configured VPC and subnet with the EFS mount setup and inspect the Infra-EmbeddedPreBuild config. Done means the 01_mount command succeeds and the Elastic Beanstalk build completes without the reported error.

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