keyword search on hg log

[TK Soh]

A couple of things I noticed on hg log --keyword :

1. hg log -h doesn't mention what fields the keyword search will be
performed against, namely the author, description and list of changed
files.

2. there appears to the a limit of 20 changes files where keyword
search will look into. This explains why the search failed when I
tried to look for the changeset on some files I added awhile back. Any
special for this limit?