Revert "consolidate repeated code in _convert_to_request_dict"

This reverts commit bd44524.

botocore/client.py

@@ -912,10 +912,20 @@ def _make_api_call(self, operation_name, api_params):
             'has_streaming_input': operation_model.has_streaming_input,
             'auth_type': operation_model.auth_type,
         }
+        api_params = self._emit_api_params(
+            api_params=api_params,
+            operation_model=operation_model,
+            context=request_context,
+        )
+        endpoint_url, additional_headers = self._resolve_endpoint_ruleset(
+            operation_model, api_params, request_context
+        )
         request_dict = self._convert_to_request_dict(
             api_params=api_params,
             operation_model=operation_model,
+            endpoint_url=endpoint_url,
             context=request_context,
+            headers=additional_headers,
         )
         resolve_checksum_context(request_dict, operation_model, api_params)
 
@@ -973,32 +983,18 @@ def _convert_to_request_dict(
         self,
         api_params,
         operation_model,
-        endpoint_url=None,
+        endpoint_url,
         context=None,
         headers=None,
         set_user_agent_header=True,
-        ignore_signing_region=False,
     ):
-        api_params = self._emit_api_params(
-            api_params=api_params,
-            operation_model=operation_model,
-            context=context,
-        )
-        endpoint_url, additional_headers = self._resolve_endpoint_ruleset(
-            operation_model=operation_model,
-            params=api_params,
-            request_context=context,
-            ignore_signing_region=ignore_signing_region,
-        )
         request_dict = self._serializer.serialize_to_request(
             api_params, operation_model
         )
         if not self._client_config.inject_host_prefix:
             request_dict.pop('host_prefix', None)
         if headers is not None:
             request_dict['headers'].update(headers)
-        if additional_headers is not None:
-            request_dict['headers'].update(additional_headers)
         if set_user_agent_header:
             user_agent = self._client_config.user_agent
         else:

botocore/signers.py

@@ -656,13 +656,25 @@ def generate_presigned_url(
         raise UnknownClientMethodError(method_name=client_method)
 
     operation_model = self.meta.service_model.operation_model(operation_name)
+    params = self._emit_api_params(
+        api_params=params,
+        operation_model=operation_model,
+        context=context,
+    )
     bucket_is_arn = ArnParser.is_arn(params.get('Bucket', ''))
+    endpoint_url, additional_headers = self._resolve_endpoint_ruleset(
+        operation_model,
+        params,
+        context,
+        ignore_signing_region=(not bucket_is_arn),
+    )
     request_dict = self._convert_to_request_dict(
         api_params=params,
         operation_model=operation_model,
+        endpoint_url=endpoint_url,
         context=context,
+        headers=additional_headers,
         set_user_agent_header=False,
-        ignore_signing_region=(not bucket_is_arn),
     )
 
     # Switch out the http method if user specified it.
@@ -770,14 +782,25 @@ def generate_presigned_post(
     # We choose the CreateBucket operation model because its url gets
     # serialized to what a presign post requires.
     operation_model = self.meta.service_model.operation_model('CreateBucket')
-    params = {'Bucket': bucket}
+    params = self._emit_api_params(
+        api_params={'Bucket': bucket},
+        operation_model=operation_model,
+        context=context,
+    )
     bucket_is_arn = ArnParser.is_arn(params.get('Bucket', ''))
+    endpoint_url, additional_headers = self._resolve_endpoint_ruleset(
+        operation_model,
+        params,
+        context,
+        ignore_signing_region=(not bucket_is_arn),
+    )
     request_dict = self._convert_to_request_dict(
         api_params=params,
         operation_model=operation_model,
+        endpoint_url=endpoint_url,
         context=context,
+        headers=additional_headers,
         set_user_agent_header=False,
-        ignore_signing_region=(not bucket_is_arn),
     )
 
     # Append that the bucket name to the list of conditions.