update '--write-pages' (#737)

- fix infinite recursion for responses with multiple entries in
  'history'
- hide values of Set-Cookie headers
- only write the response content by default
  (use '-o write-pages=all' to also include HTTP headers)

gallery_dl/extractor/common.py

@@ -328,14 +328,15 @@ class Extractor():
                 test = (test, None)
             yield test
 
-    def _dump_response(self, response):
+    def _dump_response(self, response, history=True):
         """Write the response content to a .dump file in the current directory.
 
         The file name is derived from the response url,
         replacing special characters with "_"
         """
-        for resp in response.history:
-            self._dump_response(resp)
+        if history:
+            for resp in response.history:
+                self._dump_response(resp, False)
 
         if hasattr(Extractor, "_dump_index"):
             Extractor._dump_index += 1
@@ -350,7 +351,8 @@ class Extractor():
 
         try:
             with open(fname + ".dump", 'wb') as fp:
-                util.dump_response(response, fp)
+                util.dump_response(
+                    response, fp, headers=(self._write_pages == "all"))
         except Exception as e:
             self.log.warning("Failed to dump HTTP request (%s: %s)",
                              e.__class__.__name__, e)