JHBuildで警告がエラーとして処理されるのを防ぐ方法

mutterJHBuildを使用してモジュールをビルドしようとしましたが、失敗しました。

<snip>
make[4]: Entering directory `/home/wena/src/mutter/src'
  CC     screen.lo
core/screen.c: In function 'reload_monitor_infos':
core/screen.c:445:16: error: variable 'display' set but not used [-Werror=unused-but-set-variable]
core/screen.c: At top level:
core/screen.c:394:1: error: 'find_monitor_with_rect' defined but not used [-Werror=unused-function]
core/screen.c:418:1: error: 'find_main_output_for_crtc' defined but not used [-Werror=unused-function]
cc1: all warnings being treated as errors

make[4]: *** [screen.lo] Error 1
make[4]: Leaving directory `/home/wena/src/mutter/src'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/home/wena/src/mutter/src'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/home/wena/src/mutter/src'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/wena/src/mutter'
make: *** [all] Error 2
*** Error during phase build of mutter: ########## Error running make   *** [1/1]