BLD/DOC: fix ipython_directive to workaround ipython/4504

Author: y-p

doc/sphinxext/ipython_directive.py

@@ -344,7 +344,11 @@ def process_input_line(self, line, store_history=True):
             splitter.push(line)
             more = splitter.push_accepts_more()
             if not more:
-                source_raw = splitter.source_raw_reset()[1]
+                try:
+                    source_raw = splitter.source_raw_reset()[1]
+                except:
+                    # recent ipython #4504
+                    source_raw = splitter.raw_reset()
                 self.IP.run_cell(source_raw, store_history=store_history)
         finally:
             sys.stdout = stdout