Fossil SCM

The purpose of the deltify-tkt-blobs branch is to improve handling of tickets with long text fields. This topic was initially brought up in the forum post ["RFC: Better machinery for tickets with elaborated description"] (forum:/forumpost/f5fce0764b491431).

The primary motivating example is a TICKET table with description column, accompanied by customized /tktnew, /tktview and /tktedit pages, that let a user to make arbitrary edits to ticket's description. A TICKET table may have several such columns, but for brevity any of such columns will be denoted as Description in the following.

For such ticket schema this branch brings-in three improvements:

1. Deltification of artifacts that hold edits of a ticket's Description, which enables more compact storage (and thus reduces disk usage).
   See check-ins [0f4a0fe82a, c3e7ed3089] (/vdiff?from=6f70a236ce66fa2a&to=c3e7ed308900482e)

2. Improvement to the /tkthistory page: when appropriate, changes to the Description fields are rendered as unified diffs.
   See check-ins [b75a9d0fa3, b2049d643b] (/vdiff?from=0dd5451d7f531a68&to=b2049d643b6a3a3a)

3. Resolving an issue with redundant back-references originating from outdated/superseded values within TICKET table. See check-ins [668e45baff, 4d5ded5eea] (/vdiff?from=6a5604f481d04426&to=4d5ded5eea57c709) and forum thread a6ba08e926.

How to use it

Items 1 and 2 from the above are "opt-in" features. These are activated only when a TICKET table contains a phony INTEGER column "baseline for $name", where $name stands for the name of the actual column provisioned for the aforementioned frequently changing text (e.g. "description"). This phony column "baseline for $name" is used for internal bookkeeping and must not be used by the user.

Also in this branch

Check-in adds id attributes to the list items on the /tkthistory pages, and check-in adds highlighting to the list item that is being navigated to.

Check-in fixes a missing </li>, and check-in removes [redundant PRE tags] (forum:/forumpost/924cd0f9cb2fb633) on the /wdiff pages.