tab: fix nil modification time
tab: fix nil modification time

mahori/brew,reitermarkus/brew,sjackman/homebrew,sjackman/homebrew,mahori/brew,claui/brew,MikeMcQuaid/brew,reitermarkus/brew,nandub/brew,Homebrew/brew,vitorgalvao/brew,nandub/brew,JCount/brew,JCount/brew,EricFromCanada/brew,EricFromCanada/brew,reitermarkus/brew,konqui/brew,JCount/brew,vitorgalvao/brew,Homebrew/brew,sjackman/homebrew,mahori/brew,konqui/brew,Homebrew/brew,claui/brew,nandub/brew,MikeMcQuaid/brew,reitermarkus/brew,JCount/brew,MikeMcQuaid/brew,Homebrew/brew,sjackman/homebrew,claui/brew,nandub/brew,MikeMcQuaid/brew,konqui/brew,EricFromCanada/brew,konqui/brew,mahori/brew,vitorgalvao/brew,vitorgalvao/brew,claui/brew,EricFromCanada/brew