Fix #3039: English stemmer returns wrong word if the word is capitalized

CHANGES

@@ -54,6 +54,7 @@ Bugs fixed
 * #3003: literal blocks in footnotes are not supported by Latex
 * #3047: spacing before footnote in pdf output is not coherent and allows breaks
 * #3045: HTML search index creator should ignore "raw" content if now html
+* #3039: English stemmer returns wrong word if the word is capitalized
 
 Testing
 --------

sphinx/search/en.py

@@ -242,4 +242,4 @@ class SearchEnglish(SearchLanguage):
         self.stemmer = Stemmer()
 
     def stem(self, word):
-        return self.stemmer.stem(word)
+        return self.stemmer.stem(word.lower())

tests/roots/test-search/index.rst

@@ -15,6 +15,8 @@ findthisstemmedkey
 
 textinheading
 
+International
+
 .. toctree::
 
    tocitem

tests/test_search.py

@@ -103,8 +103,10 @@ def test_stemmer_does_not_remove_short_words(app, status, warning):
 
 @with_app(testroot='search')
 def test_stemmer(app, status, warning):
-    searchindex = (app.outdir / 'searchindex.js').text()
-    assert 'findthisstemmedkei' in searchindex
+    searchindex = jsload(app.outdir / 'searchindex.js')
+    print(searchindex)
+    assert is_registered_term(searchindex, 'findthisstemmedkei')
+    assert is_registered_term(searchindex, 'intern')
 
 
 @with_app(testroot='search')