Last modified: 2011-03-13 18:05:27 UTC
For some reason when someone uses multiple lines for a template like:
it includes a new line character in the output which leads to unexpected behavior. If however you use:
a new line character is not included in the output which is the expected behavior.
This problem exists in both the new and old parser from a what a quick Special:ParserDiffTest test shows.
"| a" should be treated the same as "| 1=a" by not including a new line character.
This is ancient accidental behaviour, reproduced at great expense in the new preprocessor for the sake of backwards compatibility. We had many complaints of broken articles in the brief period when the new preprocessor did not do this. So this is how it will stay.