This happens because centos 5.5 does not support O_CLOEXEC. One workaround is to use a
newer version of Linux. Another is to edit the files in src/pkg/syscall:
zerrors_linux_386.go:625: O_CLOEXEC = 0x80000
zerrors_linux_amd64.go:625: O_CLOEXEC = 0x80000
zerrors_linux_arm.go:621: O_CLOEXEC = 0x80000
Pick the one for your architecture (or all three) and change the constant to 0 so that
the libraries know O_CLOEXEC is unsupported.