brew: Sandbox operations no longer work (`require': cannot load such file -- macho (LoadError))

• Confirmed this is a problem with Homebrew/brew and not one or more formulae? If it’s a formulae-specific problem please file this issue at https://github.com/Homebrew/homebrew-core/issues/new
• Ran brew update and retried your prior step?
• Ran brew doctor, fixed as many issues as possible and retried your prior step?
• Ran brew config and brew doctor and included their output with your issue?

Hi,

any installation or post-install command involving the sandbox fail since a recent update. This did not happen yesterday, and my system configuration did not change.

This also happens with a clean Homebrew installation.

# oliver @ Windshear in ~ [17:01:15] C:1
$ brew install cmake
==> Downloading https://homebrew.bintray.com/bottles/cmake-3.8.1.sierra.bottle.tar.gz
######################################################################## 100.0%
==> Pouring cmake-3.8.1.sierra.bottle.tar.gz
==> Using the sandbox
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- macho (LoadError)
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/os/mac/mach.rb:1:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/os/mac/pathname.rb:1:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/extend/os/mac/hardware/cpu.rb:1:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/extend/os/hardware.rb:2:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/hardware.rb:123:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/os/mac.rb:1:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/os.rb:15:in `<module:OS>'
	from /Users/oliver/.local/Library/Homebrew/os.rb:1:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/extend/os/emoji.rb:1:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/emoji.rb:14:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/utils.rb:2:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/extend/pathname.rb:4:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/global.rb:3:in `<top (required)>'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
	from /Users/oliver/.local/Library/Homebrew/postinstall.rb:3:in `<main>'
Warning: The post-install step did not complete successfully
You can try again using `brew postinstall cmake`
==> Caveats
Emacs Lisp files have been installed to:
  /Users/oliver/.local/share/emacs/site-lisp/cmake
==> Summary
/Users/oliver/.local/Cellar/cmake/3.8.1: 2,208 files, 29.2MB

# oliver @ Windshear in ~ [17:01:29] C:1
$ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry and just ignore them. Thanks!

Warning: Your Homebrew's prefix is not /usr/local.
You can install Homebrew anywhere you want but some bottles (binary packages)
can only be used with a /usr/local prefix and some formulae (packages)
may not build correctly with a non-/usr/local prefix.

Warning: Broken symlinks were found. Remove them with `brew prune`:
  /Users/oliver/.local/bin/blender
  /Users/oliver/.local/include/openssl
  /Users/oliver/.local/share/postgresql95
  /Users/oliver/.local/share/zsh/site-functions/_brew_services

# oliver @ Windshear in ~ [17:05:35] C:1
$ brew config
HOMEBREW_VERSION: 1.2.0-50-g3e4547f52
ORIGIN: https://github.com/Homebrew/brew.git
HEAD: 3e4547f52e7ebec633f8bfefc8a396d944edf908
Last commit: 2 hours ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: 9c4f788f512c3fdb9f83dace59b2194a778c13bd
Core tap last commit: 13 hours ago
HOMEBREW_PREFIX: /Users/oliver/.local
HOMEBREW_REPOSITORY: /Users/oliver/.local
HOMEBREW_CELLAR: /Users/oliver/.local/Cellar
HOMEBREW_BOTTLE_DOMAIN: https://homebrew.bintray.com
CPU: quad-core 64-bit ivybridge
Homebrew Ruby: 2.0.0-p648
Clang: 8.1 build 802
Git: 2.11.0 => /Applications/Xcode.app/Contents/Developer/usr/bin/git
Perl: /usr/bin/perl
Python: /usr/bin/python
Ruby: /usr/bin/ruby => /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
Java: 1.8.0_111, 1.6.0_65-b14-468
macOS: 10.12.4-x86_64
Xcode: 8.3.2
CLT: 8.3.2.0.1.1492020469
X11: N/A