use echo instead of printf -> problems with %

log_helpers

@@ -35,8 +35,8 @@ if [ "${log_helpers_sourced:-1}" = "1" ]; then    # include only once
             sed -e 1d -i $log_file
         fi
         local msg="$(date +'%Y-%m-%d_%T'): $*"
-        printf "log:$msg\n" >&2
-        printf "$msg\n" >> $log_file
+        echo "log:$msg" >&2
+        echo "$msg" >> $log_file
     }
 
     log_debug() {