Too late for Go 1.

http://play.golang.org/p/VsKkqRqr2U

package main
import "regexp"
var goTag = regexp.MustCompile(`^go(\.(0|[1-9][0-9]{,3}))*\.([1-9][0-9]{,3}))$`)
func main() {}

panic: regexp: Compile(`^go(\.(0|[1-9][0-9]{,3}))*\.([1-9][0-9]{,3}))$`): error parsing
regexp: regexp/syntax: internal error: ``

goroutine 1 [running]:
regexp.MustCompile(0x455e74, 0x286f675e0000002e, 0x0, 0x40a4af, 0x1, ...)
    go/src/pkg/regexp/regexp.go:197 +0x132
main.init()
    /tmpfs/gosandbox-454d834b_e6204b4b_3cffe81e_f63dfc20_02f4ec89/prog.go:5 +0x58