couldn't run az find blob in cloud shell (posh environment)

### **This is autogenerated. Please review and update as needed.**

## Describe the bug

**Command Name**
`az find`

**Errors:**
```
The command failed with an unexpected error. Here is the traceback:
string indices must be integers
Traceback (most recent call last):
File "/opt/az/lib/python3.6/site-packages/knack/cli.py", line 231, in invoke
cmd_result = self.invocation.execute(args)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 657, in execute
raise ex
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 720, in _run_jobs_serially
results.append(self._run_job(expanded_arg, cmd_copy))
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 691, in _run_job
result = cmd_copy(params)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/__init__.py", line 328, in __call__
return self.handler(*args, **kwargs)
File "/opt/az/lib/python3.6/site-packages/azure/cli/core/commands/command_operation.py", line 121, in handler
return op(**command_args)
File "/opt/az/lib/python3.6/site-packages/azure/cli/command_modules/find/custom.py", line 49, in process_query
if answer_list[0]['source'] == 'pruned':
TypeError: string indices must be integers

```

## To Reproduce:
Steps to reproduce the behavior. Note that argument values have been redacted, as they may contain sensitive information.

- _Put any pre-requisite steps here..._
- `az find {}`

## Expected Behavior

## Environment Summary
```
Linux-5.4.0-1062-azure-x86_64-with-debian-10.2 (Cloud Shell), Common Base Linux Delridge (quinault)
Python 3.6.10
Installer: DEB

azure-cli 2.29.0 *

Extensions:
ai-examples 0.2.5
ssh 0.1.6

```
## Additional Context