bazel: VSCode/Brackets + Santa cause Xcode autoconfiguration to fail on macOS

Description of the problem / feature request:

I got an error when trying to build angular (I’m on the Angular team berchet@)

The error is:

$ bazel test packages/core/test/render3
ERROR: /private/var/tmp/_bazel_berchet/136114fe9f12514cf56a27652da0b4c4/external/local_config_cc/BUILD:50:5: in apple_cc_toolchain rule @local_config_cc//:cc-compiler-darwin_x86_64: Xcode version must be specified to use an Apple CROSSTOOL
ERROR: Analysis of target '//packages/core/test/render3:render3' failed; build aborted: Analysis of target '@local_config_cc//:cc-compiler-darwin_x86_64' failed; build aborted
INFO: Elapsed time: 2.277s
FAILED: Build did NOT complete successfully (34 packages loaded)
ERROR: Couldn't start the build. Unable to run tests

Note: I had this working in the past few weeks (& using multiple times a day).

Bugs: what’s the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

On a gMac:

1. clone the angular repo at https://github.com/angular/angular
2. execute yarn into the root folder to install deps
3. execute bazel test packages/core/test/render3 at the root

yarn and bazel must be installed via brew

What operating system are you running Bazel on?

This seems to be the issue, 4 of us ran into this bug after an High Sierra 10.13.3 update

What’s the output of bazel info release?

 bazel version
Build label: 0.9.0-homebrew
Build target: bazel-out/darwin-opt/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
Build time: Sun Jul 12 12:24:01 +49936 (1513677414241)
Build timestamp: 1513677414241
Build timestamp as int: 1513677414241

Have you found anything relevant by searching the web?

I have searched the web and my team-mates, misc info

• rebooting help,
• xcode-select -s /Applications/Xcode.app/Contents/Developer before rebooting seems to help,
• when you are in a working state, never ever bazel clean you could get into the broken state

The error seems to originate in this BUILD file:

# /private/var/tmp/_bazel_berchet/136114fe9f12514cf56a27652da0b4c4/external/local_config_xcode/BUILD

package(default_visibility = ['//visibility:public'])

xcode_config(name = 'host_xcodes')
# Error: Invoking xcode-locator failed, return code 256, stderr: java.io.IOException: Cannot run program "/private/var/tmp/_bazel_berchet/136114fe9f12514cf56a27652da0b4c4/external/local_config_xcode/./xcode-locator-bin" (in directory "/private/var/tmp/_bazel_berchet/136114fe9f12514cf56a27652da0b4c4/external/local_config_xcode"): error=1, Operation not permitted, stdout: 

executing /private/var/tmp/_bazel_berchet/136114fe9f12514cf56a27652da0b4c4/external/local_config_xcode/./xcode-locator-bin fromthe CLI returns

{
	"9.2.0": "/Applications/Xcode.app/Contents/Developer",
	"9.2": "/Applications/Xcode.app/Contents/Developer",
	"9": "/Applications/Xcode.app/Contents/Developer",
}

permissions are -rwxr-xr-x

EDIT: Turned out to be an interacction with VSCode, see the fix below