extract_utils: Skip colored echo when piped

Change-Id: I8a03a36f3fa022e6858cc5c1dbca8b8037efed03
diff --git a/extract_utils.sh b/extract_utils.sh
index de62732..7d2785f 100644
--- a/extract_utils.sh
+++ b/extract_utils.sh
@@ -1800,7 +1800,7 @@
         white|*) color=7 ;; # white or invalid color
         esac
     fi
-    tput setaf $color
+    if [ -t 1 ] ; then tput setaf $color; fi
     printf '%s\n' "$*"
-    tput sgr0
+    if [ -t 1 ] ; then tput sgr0; fi
 }