[RFC PATCH 1/4] blame: prefer null_sha1 over nullid and retire later

["Carlo Marcelo Arenas Belón" <carenas@gmail.com>]

a9786bb (git-gui: Fix Blame Parent & Context for working copy lines.,
2008-09-08) adds nullid (and a never used nullid2) for matching locally
modified lines in blame.

Use instead the already available null_sha1 for the same and in
preparation to making that hash independent on a future patch.

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
---
 git-gui.sh    |  3 ---
 lib/blame.tcl | 10 +++++-----
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/git-gui.sh b/git-gui.sh
index 201524c..a69b0fe 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -1353,9 +1353,6 @@ set diff_empty_count 0
 set last_revert {}
 set last_revert_enc {}
 
-set nullid "0000000000000000000000000000000000000000"
-set nullid2 "0000000000000000000000000000000000000001"
-
 ######################################################################
 ##
 ## task management
diff --git a/lib/blame.tcl b/lib/blame.tcl
index 8441e10..6ece79d 100644
--- a/lib/blame.tcl
+++ b/lib/blame.tcl
@@ -1056,14 +1056,14 @@ method _format_offset_date {base offset} {
 }
 
 method _gitkcommit {} {
-	global nullid
+	global null_sha1
 
 	set dat [_get_click_amov_info $this]
 	if {$dat ne {}} {
 		set cmit [lindex $dat 0]
 
 		# If the line belongs to the working copy, use HEAD instead
-		if {$cmit eq $nullid} {
+		if {$cmit eq $null_sha1} {
 			if {[catch {set cmit [git rev-parse --verify HEAD]} err]} {
 				error_popup [strcat [mc "Cannot find HEAD commit:"] "\n\n$err"]
 				return;
@@ -1106,7 +1106,7 @@ method _gitkcommit {} {
 }
 
 method _blameparent {} {
-	global nullid
+	global null_sha1
 
 	set dat [_get_click_amov_info $this]
 	if {$dat ne {}} {
@@ -1114,7 +1114,7 @@ method _blameparent {} {
 		set new_path [lindex $dat 1]
 
 		# Allow using Blame Parent on lines modified in the working copy
-		if {$cmit eq $nullid} {
+		if {$cmit eq $null_sha1} {
 			set parent_ref "HEAD"
 		} else {
 			set parent_ref "$cmit^"
@@ -1129,7 +1129,7 @@ method _blameparent {} {
 		# Generate a diff between the commit and its parent,
 		# and use the hunks to update the line number.
 		# Request zero context to simplify calculations.
-		if {$cmit eq $nullid} {
+		if {$cmit eq $null_sha1} {
 			set diffcmd [list diff-index --unified=0 $cparent -- $new_path]
 		} else {
 			set diffcmd [list diff-tree --unified=0 $cparent $cmit -- $new_path]
-- 
2.33.0.1081.g099423f5b7