Details -- thanks, @jreback

Author: adamhooper

doc/source/whatsnew/v0.24.0.txt

@@ -24,7 +24,7 @@ Other Enhancements
   <https://pandas-gbq.readthedocs.io/en/latest/changelog.html#changelog-0-5-0>`__.
   (:issue:`21627`)
 - New method :meth:`HDFStore.walk` will recursively walk the group hierarchy of an HDF5 file (:issue:`10932`)
-- :func:`read_html` handles colspan and rowspan arguments and attempts to infer a header if the header is not explicitly specified (:issue:`17054`)
+- :func:`read_html` copies cell data across ``colspan``s and ``rowspan``s, and it treats all-``th`` table rows as headers if ``header`` kwarg is not given and there is no ``thead`` (:issue:`17054`)
 -
 
 .. _whatsnew_0240.api_breaking:

pandas/io/html.py

@@ -378,6 +378,8 @@ def _parse_thead_tbody_tfoot(self, table_html):
         """
         Given a table, return parsed header, body, and foot.
 
+        Notes
+        -----
         Header and body are lists-of-lists. Top level list is a list of
         rows. Each row is a list of str text.
 
@@ -700,9 +702,6 @@ def _parse_tables(self, doc, match, kwargs):
     def _equals_tag(self, obj, tag):
         return obj.tag == tag
 
-    def _contains_tag(self, obj, tag):
-        return obj.find(tag) is not None
-
     def _build_doc(self):
         """
         Raises