[m-rev.] diff: simplify away unneeded yes() wrappers

[Zoltan Somogyi]

This follows on from the Mantis 476 bug fix.

Zoltan.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Log.mppid
Type: application/octet-stream
Size: 266 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20190408/00ff91de/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: DIFF.mppid
Type: application/octet-stream
Size: 9985 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20190408/00ff91de/attachment-0001.obj>