[PATCH v2] gitk: fix direction of symmetric difference in optimized mode

[Thomas Rast <trast@student.ethz.ch>]

ee66e08 (gitk: Make updates go faster, 2008-05-09) implemented an
optimized mode where gitk parses the arguments with rev-parse, and
manually reads history in chunks.  As mentioned in the commit message,
symmetric differences are a problem there:

    One wrinkle is that we have to turn symmetric diff arguments (of the
    form a...b) back into symmetric diff form so that --left-right still
    works, as git rev parse turns a...b into a b ^merge_base(a,b).

However, git-rev-parse returns a...b in the swapped order

    b a ^merge_base(a,b)

This has been the case since at least 1f8115b (the state of master at
the time of the abovementioned ee66e08; Merge branch 'maint',
2008-05-08).  So gitk flipped the sides of symmetric differences
whenever it was in optimized mode.

Fix this by swapping the sides of the reconstruction code.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
---

This supersedes the older patch, which was simply wrong; the triangle
directions in the affected section are correct.

The confusing part of this, but also how I stumbled across the real
bug, was that I was playing with --show-all and that flipped the
direction *again*.  Turns out the option is not recognized by gitk and
lets it go back to unoptimized mode, where the bug does not exist.


 gitk |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/gitk b/gitk
index 4604c83..e103dab 100755
--- a/gitk
+++ b/gitk
@@ -288,7 +288,7 @@ proc parseviewrevs {view revs} {
 	    if {$sdm != 2} {
 		lappend ret $id
 	    } else {
-		lset ret end [lindex $ret end]...$id
+		lset ret end $id...[lindex $ret end]
 	    }
 	    lappend pos $id
 	}
-- 
1.6.4.96.g577b