Build failure thanks to web ui merge

[srh]

I get this as a result of the recent web ui merge in #6344.

   [607/616] COFFEE build/drivers/javascript/coffee/util.js
    [608/616] CP ./build/packages/js
    [609/616] CP build/packages/js/node_modules/bluebird
    [610/616] BROWSERIFY build/drivers/javascript/rethinkdb.js
    [611/616] CP build/web_assets/rethinkdb.js
    [612/616] COFFEE build/web_assets/cluster.js
    [613/616] LESSC build/web_assets/cluster.css
/usr/bin/env: node: No such file or directory

Full error log: ./build/web_assets_js.log
admin/build.mk:27: recipe for target 'build/web_assets/cluster.js' failed
make[1]: *** [build/web_assets/cluster.js] Error 1
/usr/bin/env: node: No such file or directory

Full error log: ./build/web_assets_css.log
admin/build.mk:31: recipe for target 'build/web_assets/cluster.css' failed
make[1]: *** [build/web_assets/cluster.css] Error 1
make[1]: Target 'default-goal' not remade because of errors.
Makefile:52: recipe for target 'make' failed
make: *** [make] Error 2

On Debian Jessie with ./configure --allow-fetch CXX=clang++

[AtnNn]

Sorry about that. I'll fix that soon. Meanwhile I think adding build/external/node_6.10.0/bin to your path might help.