Move and correct defn

The salient difference is that it uses -x when testing.

_reformat-common.bash

@@ -103,18 +103,6 @@ function custom_sniff() {
     fi
 }
 
-function custom_formatter() {
-    root="$1"
-    file_type="$2"
-
-    maybe="$root/.would-reformat/$file_type"
-    if [[ -f "$maybe" ]]; then
-        echo "$maybe"
-        return
-    fi
-
-    echo "use-default"
-}
 
 ## WOULD_FORMAT_PROJECT_ROOT=$(project_root $1)
 
@@ -165,6 +153,19 @@ function sniff_file_type() {
     echo $file_type
 }
 
+function custom_formatter() {
+    root="$1"
+    file_type="$2"
+
+    maybe="$root/.would-reformat/$file_type"
+    if [[ -x "$maybe" ]]; then
+        echo -n "$maybe"
+        return
+    fi
+
+    echo ""
+}
+
 function choose_wrapper() {
     file_type="$1"