Open Radar

 
Summary:
When preprocessing an entitlements file during a build, it doesn't respect values passed on the commandline to xcodebuild.

Steps to Reproduce:
1) Put a pre-processed value in the `my-app.entitlements` file for my app.  For example:
```
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>com.apple.security.application-groups</key>
	<array>
		<string>$(MY_APP_GROUP)</string>
	</array>
</dict>
</plist>
```

2) Build from the command-line, using `xcodebuild`, passing a value for `MY_APP_GROUP` as an argument.
```
$ xcodebuild -scheme MyApp -configuration release build MY_APP_GROUP=my-container-value`
```

Expected Results:
The value from the command-line should be filled in to the entitlements file during the pre-processing phase.

Observed Results:
It's not filled in.

If there is a value for MY_APP_GROUP set elsewhere in the build settings (e.g. in the Xcode gui, or a xcconfig file), then that value is used.  But the value from the command-line arg should take higher priority, but it doesn't.

This used to work correctly in Xcode 8.2.

Version:
Xcode 8.3.2
Build version 8E2002

macOS Sierra 10.12.5 (16F73)