Description of problem:
Building module locally throws exception (see Actual results).

Version-Release number of selected component (if applicable):
module-build-service-2.14.0-2.fc29.noarch

How reproducible:
always

Steps to Reproduce:
1. rhpkg module-build-local
2.
3.

Actual results:
2019-03-07 14:44:36,613 - MainThread - urllib3.util.retry - DEBUG - Converted retries value: 3 -> Retry(total=3, connect=None, read=None, redirect=None, status=None)
2019-03-07 14:44:36,808 - MainThread - moksha.hub - WARNING - Cannot find qpid python module. Make sure you have python-qpid installed.
Traceback (most recent call last):
  File "/usr/bin/mbs-manager", line 11, in <module>
    load_entry_point('module-build-service==2.14.0', 'console_scripts', 'mbs-manager')()
  File "/usr/lib/python3.7/site-packages/module_build_service/manage.py", line 238, in manager_wrapper
    manager.run()
  File "/usr/lib/python3.7/site-packages/flask_script/__init__.py", line 417, in run
    result = self.handle(argv[0], argv[1:])
  File "/usr/lib/python3.7/site-packages/flask_script/__init__.py", line 386, in handle
    res = handle(*args, **config)
  File "/usr/lib/python3.7/site-packages/flask_script/commands.py", line 216, in __call__
    return self.run(*args, **kwargs)
  File "/usr/lib/python3.7/site-packages/module_build_service/manage.py", line 154, in build_module_locally
    username, handle, str(stream), skiptests, optional_params)
  File "/usr/lib/python3.7/site-packages/module_build_service/utils/submit.py", line 400, in submit_module_build_from_yaml
    yaml_file = handle.read().decode("utf-8")
AttributeError: 'str' object has no attribute 'decode'
Could not execute module_build_local: Failed to execute command.


Expected results:
Building works, no tracebacks.

Additional info:
Downgrading to module-build-service-2.12.2-1.fc29.noarch makes this work again.