git gui: fix branch name encoding error

After "git checkout -b '漢字'" to create a branch with UTF-8 character
in it, "git gui" shows the branch name incorrectly, as it forgets to
turn the bytes read from the "git for-each-ref" and read from "HEAD"
file into Unicode characters.

Signed-off-by: Kazuhiro Kato <kato-k@ksysllc.co.jp>
Signed-off-by: Pratyush Yadav <me@yadavpratyush.com>

git-gui.sh

@@ -684,6 +684,7 @@ proc load_current_branch {} {
 	global current_branch is_detached
 
 	set fd [open [gitdir HEAD] r]
+	fconfigure $fd -translation binary -encoding utf-8
 	if {[gets $fd ref] < 1} {
 		set ref {}
 	}

lib/branch.tcl

@@ -8,6 +8,7 @@ proc load_all_heads {} {
 	set rh_len [expr {[string length $rh] + 1}]
 	set all_heads [list]
 	set fd [git_read for-each-ref --format=%(refname) $rh]
+	fconfigure $fd -translation binary -encoding utf-8
 	while {[gets $fd line] > 0} {
 		if {!$some_heads_tracking || ![is_tracking_branch $line]} {
 			lappend all_heads [string range $line $rh_len end]
@@ -24,6 +25,7 @@ proc load_all_tags {} {
 		--sort=-taggerdate \
 		--format=%(refname) \
 		refs/tags]
+	fconfigure $fd -translation binary -encoding utf-8
 	while {[gets $fd line] > 0} {
 		if {![regsub ^refs/tags/ $line {} name]} continue
 		lappend all_tags $name