Simplified fail-safe #116

jupytext/cell_metadata.py

@@ -319,17 +319,14 @@ def is_active(ext, metadata):
 def double_percent_options_to_metadata(options):
     """Parse double percent options"""
     matches = _PERCENT_CELL.findall('# %%' + options)
-    if matches == []: ## didn't match with options
-        matches = _PERCENT_CELL.findall('# %%')
-        ## assume a code cell, with extra stuff
-        if matches == []: ## didn't match at all
-            return {}
-        else:
-            ## Put rest of line in title metadata:
-            matches = list(matches[0])
-            matches[1] = options
-    else:
-        matches = matches[0]
+
+    # Fail safe when regexp matching fails #116
+    # (occurs e.g. if square brackets are found in the title)
+    if not matches:
+        return {'title': options.strip()}
+
+    matches = matches[0]
+
     # Fifth match are JSON metadata
     if matches[4]:
         metadata = json_options_to_metadata(matches[4], add_brackets=False)