Fix Python DELETE bug introduced in earlier commit

The earlier commit 9dfe1f6 introduced a bug for `DELETE` requests on the
standard Python generator.  This commit fixes that bug and also includes
the updated samples.

Author: johnboyes

modules/openapi-generator/src/main/resources/python/rest.mustache

@@ -137,7 +137,7 @@ class RESTClientObject(object):
                     headers['Content-Type'] = 'application/json'
                 if query_params:
                     url += '?' + urlencode(query_params)
-                if re.search('json', headers['Content-Type'], re.IGNORECASE):
+                if ('Content-Type' not in headers) or (re.search('json', headers['Content-Type'], re.IGNORECASE)):
                     request_body = None
                     if body is not None:
                         request_body = json.dumps(body)

samples/client/petstore/python/petstore_api/rest.py

@@ -145,7 +145,7 @@ def request(self, method, url, query_params=None, headers=None,
                     headers['Content-Type'] = 'application/json'
                 if query_params:
                     url += '?' + urlencode(query_params)
-                if re.search('json', headers['Content-Type'], re.IGNORECASE):
+                if ('Content-Type' not in headers) or (re.search('json', headers['Content-Type'], re.IGNORECASE)):
                     request_body = None
                     if body is not None:
                         request_body = json.dumps(body)

samples/client/petstore/python_disallowAdditionalPropertiesIfNotPresent/petstore_api/rest.py

@@ -145,7 +145,7 @@ def request(self, method, url, query_params=None, headers=None,
                     headers['Content-Type'] = 'application/json'
                 if query_params:
                     url += '?' + urlencode(query_params)
-                if re.search('json', headers['Content-Type'], re.IGNORECASE):
+                if ('Content-Type' not in headers) or (re.search('json', headers['Content-Type'], re.IGNORECASE)):
                     request_body = None
                     if body is not None:
                         request_body = json.dumps(body)

samples/openapi3/client/extensions/x-auth-id-alias/python/x_auth_id_alias/rest.py

@@ -145,7 +145,7 @@ def request(self, method, url, query_params=None, headers=None,
                     headers['Content-Type'] = 'application/json'
                 if query_params:
                     url += '?' + urlencode(query_params)
-                if re.search('json', headers['Content-Type'], re.IGNORECASE):
+                if ('Content-Type' not in headers) or (re.search('json', headers['Content-Type'], re.IGNORECASE)):
                     request_body = None
                     if body is not None:
                         request_body = json.dumps(body)

samples/openapi3/client/features/dynamic-servers/python/dynamic_servers/rest.py

@@ -145,7 +145,7 @@ def request(self, method, url, query_params=None, headers=None,
                     headers['Content-Type'] = 'application/json'
                 if query_params:
                     url += '?' + urlencode(query_params)
-                if re.search('json', headers['Content-Type'], re.IGNORECASE):
+                if ('Content-Type' not in headers) or (re.search('json', headers['Content-Type'], re.IGNORECASE)):
                     request_body = None
                     if body is not None:
                         request_body = json.dumps(body)

samples/openapi3/client/petstore/python/petstore_api/rest.py

@@ -145,7 +145,7 @@ def request(self, method, url, query_params=None, headers=None,
                     headers['Content-Type'] = 'application/json'
                 if query_params:
                     url += '?' + urlencode(query_params)
-                if re.search('json', headers['Content-Type'], re.IGNORECASE):
+                if ('Content-Type' not in headers) or (re.search('json', headers['Content-Type'], re.IGNORECASE)):
                     request_body = None
                     if body is not None:
                         request_body = json.dumps(body)