Mono JIT compiler version 4.2.1 (Debian 4.2.1.102+dfsg2-7ubuntu4).

$ mono -V
Mono JIT compiler version 3.12.1 (tarball Fri Mar  6 19:12:47 UTC 2015)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
    TLS:           __thread
    SIGSEGV:       altstack
    Notifications: epoll
    Architecture:  amd64
    Disabled:      none
    Misc:          softdebug
    LLVM:          supported, not enabled.
    GC:            sgen