user-manual: minor rewording for clarity.

diff --git a/git-mergetool.sh b/git-mergetool.sh
index 94511f9d1ace4e41bd225cd25643b17770b075b1..a68b40386bde1c47c33a19514ec3a22db7fb0e4b 100755 (executable)
--- a/git-mergetool.sh
+++ b/git-mergetool.sh
@@ -334,7 +334,7 @@ init_merge_tool_path() {
 
 if test -z "$merge_tool"; then
     merge_tool=`git config merge.tool`
-    if ! valid_tool "$merge_tool"; then
+    if test -n "$merge_tool" && ! valid_tool "$merge_tool"; then
            echo >&2 "git config option merge.tool set to unknown tool: $merge_tool"
            echo >&2 "Resetting to default..."
            unset merge_tool