react-native start not using passed --sourceExts

[elyalvarado]

Environment

React Native Environment Info:
System:
OS: macOS High Sierra 10.13.6
CPU: x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
Memory: 32.02 MB / 16.00 GB
Shell: 5.3 - /bin/zsh
Binaries:
Node: 8.12.0 - ~/.nvm/versions/node/v8.12.0/bin/node
Yarn: 1.10.1 - /usr/local/bin/yarn
npm: 6.4.1 - ~/.nvm/versions/node/v8.12.0/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
SDKs:
iOS SDK:
Platforms: iOS 11.4, macOS 10.13, tvOS 11.4, watchOS 4.3
Android SDK:
Build Tools: 27.0.3
API Levels: 27
IDEs:
Android Studio: 3.1 AI-173.4907809
Xcode: 9.4.1/9F2000 - /usr/bin/xcodebuild
npmPackages:
react: 16.5.0 => 16.5.0
react-native: 0.57.0 => 0.57.0

Also tested with the latest react-native version (0.57.3)

Description

When starting the react-native packager either by using react-native start --sourceExts e2e.js, or by directly calling the local-cli included with the react-native package in node_modules the packager is not prioritizing the passed source extension.

Reproducible Demo

react-native init TestProject
cd TestProject
cp App.js App.e2e.js
# Make a visible change in App.e2e.js
react-native start --sourceExts e2e.js
react-native run-ios
# Check to see that the packager is not taking the e2e.js file

[hramos]

The command line tools have their own repository and issue tracker over at https://github.com/react-native-community/react-native-cli.