When a line starts with an exclamation mark, parsoid removes the exclamation mark, and also when there's a space before the exclamation mark (it respects the space).
For example:
INPUT:
!1
OUTPUT:
1
INPUT:
!1
OUTPUT:
<nowiki> 1</nowiki>
See URL for example.
I discovered it reviewing this edit:
http://www.mediawiki.org/w/index.php?diff=716121
I don't know if the "General" component is correct.
Version: unspecified
Severity: normal
URL: https://www.mediawiki.org/wiki/User:Ciencia_Al_Poder/Parsoid/1