(Bug 25254) cl_timestamp gets updated on null edit where it shouldn't.

(Bug 25254) cl_timestamp gets updated on null edit where it shouldn't.
Caused by two things:
*after the new category collation stuff, the if this category has changed
code was comparing the user supplied sortkey, with the collation sortable
sortkey, which didn't work. (See also CR for r70415) This is new issue in 1.17
*If the sortkey was too long (long enough to get truncated by DB), then the
did this sortkey change code also failed since it was  comparing the
non-truncated sortkey to the truncated sortkey. This issue is present
in older (all previous?) versions of mediawiki. This issue especially affects
non-latin wikis that use 3-byte characters.

This bug primarily is an issue for people using DPL type extension.

I wasn't sure if i should add RELEASE-NOTES, since i'm tagging this 1.17