Using rule:
'header/header': [2, 'line', 'my header comment.']
with file:
// my header comment.
console.log(1);
reports incorrect header. Changing rule to:
'header/header': [2, 'line', ' my header comment.']
will not report error and unblocks use.
In both rule cases --fix will produce:
// my header comment.
console.log(1);
if error is detected. (Added line per issue #24 Autofix adds new line has been removed.)
In my setup, I am using eslint 6.8.0.