Merge pull request #3964 from shin-/3963-unicode-env

Don't break when interpolating environment with unicode characters

compose/service.py

@@ -1111,6 +1111,8 @@ def format_environment(environment):
     def format_env(key, value):
         if value is None:
             return key
+        if isinstance(value, six.binary_type):
+            value = value.decode('utf-8')
         return '{key}={value}'.format(key=key, value=value)
     return [format_env(*item) for item in environment.items()]