Fix empty cell in table header causes LaTeX error (#1574)

sphinx/writers/latex.py

@@ -1061,6 +1061,9 @@ class LaTeXTranslator(nodes.NodeVisitor):
                 self.remember_multirowcol[self.table.col] = node.get('morecols')
             self.table.col += node.get('morecols')
         if isinstance(node.parent.parent, nodes.thead):
+            if len(node) == 1 and isinstance(node[0], nodes.paragraph) and node.astext() == '':
+                pass
+            else:
                 self.body.append('\\textsf{\\relax ')
                 context += '}'
         while self.remember_multirow.get(self.table.col + 1, 0):

tests/root/markup.txt

@@ -187,6 +187,15 @@ Tables
    | 2  | Empty cells:   |    |
    +----+----------------+----+
 
+.. table:: empty cell in table header
+
+   ===== ======
+   \ 
+   ===== ======
+   1     2
+   3     4
+   ===== ======
+
 Tables with multirow and multicol:
 
 .. only:: latex