Build script problem with gnupg 2.1.3

[Mike Ingle]

I am building gnupg 2.1.3 to try out, and I ran into a bug in the build 
script.
If you run ./configure --help in libgcrypt-1.6.3, it says:

Optional Packages:
  --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
  --without-PACKAGE       do not use PACKAGE (same as --with-PACKAGE=no)
  --with-pic[=PKGS]       try to use only PIC/non-PIC objects [default=use
                          both]
  --with-gnu-ld           assume the C compiler uses GNU ld [default=no]
  --with-sysroot=DIR Search for dependent libraries within DIR
                        (or the compiler's sysroot if not specified).
  --with-egd-socket=NAME  Use NAME for the EGD socket)
  --with-capabilities     Use linux capabilities [default=no]
  --with-libgpg-error-prefix=PFX
                          prefix where GPG Error is installed (optional)

  --with-pth-prefix=PFX   prefix where GNU Pth is installed (optional)

However, the libgpg-error-prefix doesn't actually work. You have to use:
--with-gpg-error-prefix=

Mike