[BUGLET] git bisect visualize does not show BISECT_HEAD

[Yann Dirson <dirson@bertin.fr>]

[v1.8.3.4]

"git bisect visualize" when run without --no-checkout has the standard gitk handling of
"HEAD" showing what the current revision being tested is (as a yellow node).

Now when using --no-checkout, the information "current revision" we may be looking for
has nothing to do with HEAD any longer: we need BISECT_HEAD instead - and if by any chance
HEAD would happen to be in the displayed scope, the user may do wrong assumptions about
it (maybe).


Wondering whether there would be any flags that would pass to gitk through "bisect visualize",
I naively tried:

 $ git bisect visualize -h
 usage: git log [<options>] [<revision range>] [[--] <path>...]
   or: git show [options] <object>...

    --quiet               suppress diff output
    --source              show source
    --use-mailmap         Use mail map file
    --decorate[=...]      decorate options
    -L <n,m:file>         Process line range n,m in file, counting from 1

Wandering away from what I was look for:

 $ git bisect visualize --decorate
 ... some git log output

That seems unfortunate in its own right as well...


Back to the problem of visualizing the info, it looks like gitk would need a way to display
refs that are not displayed by default, when we need them.  Something like:

	gitk --explicit-refs=BISECT_HEAD,refs/whatever

That would also be helpful when one tries to look at the reflog graphically: whereas
gitk accepts to show whatever@{1} and friends, it never tells us which revision corresponds
to which reflog entry, and --explicit-refs=whatever@{1},whatever@{2} would help here, as would
something like --explicit-refs=whatever@{*} or --explicit-refs=whatever@{1..5}, but that starts
to be more tricky to formalize.

Thoughts, anyone ?

-- 
Yann Dirson - Bertin Technologies