simctl not working in Xcode 7.0 and Xcode 7.1 beta 1 - backboardd not loaded

UPDATED FOR Xcode 7

In Xcode 7.0, I have not been able to install or uninstall apps with simctl.

And there is a typo in the simctl help:

$ xcrun simctl help
...
get_app_container  Print the path of the **intsalled** app's container
...

Reproduce

$ export DEVICE=F24BE4F9-36C5-4842-84A4-1EA2614B8A3E
$ export APP=/path/to/CalSmoke-cal.app

$ xcrun simctl boot $DEVICE
$ xcrun simctl install $DEVICE $PATH

Expected

To see the app installed on the target simulator.

Found

The command hangs indefinitely. Xcode 7 GM

$ xcrun simctl install $DEVICE $PATH
An error was encountered processing the command (domain=NSPOSIXErrorDomain, code=2):
Failed to install the requested application
An application bundle was not found at the provided path.
Provide a valid path to the desired application bundle.

The APP does exist at path.

The Simulator log shows that `backboard` is not loaded; that log message repeats indefinitely.

$ tail -f ~/Library/Logs/CoreSimulator/F24BE4F9-36C5-4842-84A4-1EA2614B8A3E
stern CoreSimulatorBridge[8316]: Requesting installation of file:///Users/moody/git/calabash/ios-smoke-test-app/CalSmokeApp/CalSmoke-cal.app/ with options: {
    CFBundleIdentifier = "sh.calaba.CalSmoke-cal";
    PackageType = Developer;
    SimulatorRootPath = "/Xcode/7.0/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk";
    SimulatorUserPath = "/Users/moody/Library/Developer/CoreSimulator/Devices/F24BE4F9-36C5-4842-84A4-1EA2614B8A3E/data";
  }
stern CoreSimulatorBridge[8316]: LaunchServices: installing app for existing placeholder <LSApplicationProxy: 0x7fd5e3700580> sh.calaba.CalSmoke-cal <(null) *Not found in database*>
stern CoreSimulatorBridge[8316]: LaunchServices: Not creating progress for <LSApplicationProxy: 0x7fd5e3700580> sh.calaba.CalSmoke-cal <(null) *Not found in database*> since it is not a placeholder.
stern installd[8290]: 0x112481000 -[MIClientConnection installPath:withOptions:completion:]: Install of "/Users/moody/git/stern installd[8290]: 0x111bfc000 -[MIInstaller _extractPackageWithError:]: Did not construct delta; doing full copy for installation.
stern SpringBoard[8300]: BSXPCMessage received error for message: Connection invalid
--- last message repeated 1 time ---
stern SpringBoard[8300]: -[BKSSystemApplicationClient queue_connectionWasInvalidated] backboardd is not loaded; waiting for it to return.
stern SpringBoard[8300]: BSXPCMessage received error for message: Connection invalid
--- last message repeated 1 time ---
stern SpringBoard[8300]: -[BKSSystemApplicationClient queue_connectionWasInvalidated] backboardd is not loaded; waiting for it to return.

stern ***[8341]: LaunchServices: Currently 0 installed placeholders: (
  )
stern SpringBoard[8300]: BSXPCMessage received error for message: Connection invalid
--- last message repeated 1 time ---
stern SpringBoard[8300]: -[BKSSystemApplicationClient queue_connectionWasInvalidated] backboardd is not loaded; waiting for it to return.

Regression

1. Xcode 6.0 - 6.4 - works as expected.
2. Xcode 7.1 beta 1 - same result as Xcode 7.0 GM
3. The same behavior occurs with any app.

Notes

If the app is already installed and I try to uninstall, the command also hangs.

The software I maintain requires that I have many side-by-side installations of Xcode (back to Xcode 5.1.1). They are installed like this:

/Xcode/5.1.1/Xcode.app
...
/Xcode/6.4/Xcode.app
/Xcode/7.0/Xcode.app
/Xcode/7.1b1/Xcode-beta.app

• I have restarted my machine several times.
• The app can be built and installed from any Xcode.
• The app can be installed and launched with instruments from any Xcode.
• I tried with --noxpc (something I don't usually do).
• I ensured that all simulators were launched at least once and ensured they have finished installing their content.

MacOS Yosemite 10.10.5 (14F27)