Escape underscore in citation labels for latex export

sphinx/writers/latex.py

@@ -382,7 +382,7 @@ class LaTeXTranslator(nodes.NodeVisitor):
                 target = self.hypertarget(bi[2] + ':' + bi[3],
                                           withdoc=False)
                 self.body.append(u'\\bibitem[%s]{%s}{%s %s}\n' %
-                    (bi[0], self.idescape(bi[0]), target, bi[1]))
+                    (self.encode(bi[0]), self.idescape(bi[0]), target, bi[1]))
             self.body.append(u'\\end{thebibliography}\n')
             self.bibitems = []
 

tests/root/contents.txt

@@ -43,3 +43,4 @@ References
 ==========
 
 .. [Ref1] Reference target.
+.. [Ref_1] Reference target 2.

tests/root/markup.txt

@@ -240,6 +240,7 @@ Misc stuff
 Stuff [#]_
 
 Reference lookup: [Ref1]_ (defined in another file).
+Reference lookup underscore: [Ref_1]_
 
 .. seealso:: something, something else, something more