mergetool-lib: give kdiff3 priority in KDE environments

Signed-off-by: Marco Trevisan (Treviño) <mail@3v1n0.net>

Author: 3v1n0

git-mergetool--lib.sh

@@ -289,6 +289,9 @@ list_merge_tool_candidates () {
 		if is_desktop "GNOME" || if test -n "$GNOME_DESKTOP_SESSION_ID"
 		then
 			tools="meld opendiff kdiff3 tkdiff xxdiff $tools"
+		elif is_desktop "KDE"
+		then
+			tools="kdiff3 opendiff tkdiff xxdiff meld $tools"
 		else
 			tools="opendiff kdiff3 tkdiff xxdiff meld $tools"
 		fi