ember-cli: Build/Serve changes are not detected for app.import files that have outputFile option

I have a file under vendor like so: vendor/shared.js and this line in ember-cli-build.js:

app.import('vendor/shared.js', { outputFile: 'assets/shared-ui.js' });

ember b and ember s output the file correctly, but changes to the file while using ember s or ember b -w are not detected for this file.

Output from ember version --verbose && npm --version:

ember-cli: 2.8.0
http_parser: 2.7.0
node: 6.6.0
v8: 5.1.281.83
uv: 1.9.1
zlib: 1.2.8
ares: 1.10.1-DEV
icu: 57.1
modules: 48
openssl: 1.0.2h
os: darwin x64
3.10.3