Add explanatory comments

Also, remove line which was accidentally removed

templating/build.py

@@ -76,6 +76,11 @@ def main(input_module, file_stream=None, out_dir=None, verbose=False):
         return " "*indent + input
 
     def wrap(input, wrap=80, initial_indent=""):
+        if len(input) == 0:
+            return initial_indent
+        # TextWrapper collapses newlines into single spaces; we do our own
+        # splitting on newlines to prevent this, so that newlines can actually
+        # be intentionally inserted in text.
         input_lines = input.split('\n\n')
         wrapper = TextWrapper(initial_indent=initial_indent, width=wrap)
         output_lines = [wrapper.fill(line) for line in input_lines]