title: Can't export signing identity from Xcode
body: <p>I go to Xcode preferences, Accounts. Select my developer account and select "Export Accounts" from the gear at the bottom of the dialog. I'm presented with a dialog, I select the location, give it a file name, enter a password in both fields and click OK. I get this error message:
  "The specified item already exists in the keychain."</p>
  
  <p>What's that all about and how do I export my signing identity?</p>