I upgraded my Mac to 10.10.3 and Xcode to 6.3.1 yesterday; today I can\'t use git, codesign_allocate....and more.
codesign_allocate
`sh: line 1: 18421 Abort trap:
Have you tried if xcodebuild command work as expected and if you have any Xcode plugins in the plugins Folder located at ~/Library/Application\ Support/Developer/Shared/Xcode/Plug-ins who can cause this issue.
xcodebuild
~/Library/Application\ Support/Developer/Shared/Xcode/Plug-ins