When a comment ended before the end of a paragraph, the next
comment would begin right there in the middle of the paragraph.
This could result in the detected indentation level of that
comment being incorrect, and replies being inserted in wrong
places, as seen in the 'signatures-funny' test case.
The code moved to the parser was previously repeated twice in
addListItem() and addReplyLink(), which should have been a hint
that something isn't quite right.
Also, fix the code guarding against overlapping signatures,
now that signatures may not be at the end of a comment.
Bug: T260855
Change-Id: Ic26a87642f8a15d5de2f7073d4d8176b299c7f94
Expand the 'signatures-funny' test case with more examples, which
don't behave correctly.
Follow-up commits I04a8ea09401e06f2d4bb1f226f17eb528b29ed95 and
Ic26a87642f8a15d5de2f7073d4d8176b299c7f94 fix them.
Bug: T255738
Change-Id: I0fdd8bdf11b497ffeed37c37953c5730f6e4f3b7
