GnuPG and --no-emit-version

I'm using GnuPG v1.4.15 on Slackware 14.1:

bash-4.2$ gpg --version
gpg (GnuPG) 1.4.15
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: ~/.gnupg
Supported algorithms:
Pubkey: RSA, RSA-E, RSA-S, ELG-E, DSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
        CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: MD5, SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed, ZIP, ZLIB, BZIP2
bash-4.2$ uname -a
Linux magnentius 3.10.17 #2 SMP Wed Oct 23 16:34:38 CDT 2013 x86_64 AMD C-50 Processor AuthenticAMD GNU/Linux
bash-4.2$ cat /etc/*version*
Slackware 14.1
bash-4.2$


The GnuPG help doesn't mention no-emit-version:

bash-4.2$ gpg --help | grep no-emit-version
bash-4.2$


Let's check if it works by exporting a public key and playing with the output.  I've imported Alan Rusbridger's key, linked from his twitter feed: https://twitter.com/arusbridger from here: http://static.guim.co.uk/ni/1393869928289/Public-Key.asc (The Guardian used GnuPG 1.4.11 to export that key...)

bash-4.2$ gpg --list-keys
/home/chrism/.gnupg/pubring.gpg
-------------------------------
pub   2048R/576F0B0D 2013-08-21
uid                  Alan Rusbridger (Ed) <alan.rusbridger@theguardian.com>
sub   2048R/3406B7C8 2013-08-21

bash-4.2$ gpg --export --armor 576F0B0D
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v1.4.15 (GNU/Linux)
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=NK7s
-----END PGP PUBLIC KEY BLOCK-----
bash-4.2$


As expected we can see I'm using GnuPG 1.4.15, as is standard (I think) for Slackware 14.1.  Now try the --no-emit-version parameter:

bash-4.2$ gpg --no-emit-version --export --armor 576F0B0D
-----BEGIN PGP PUBLIC KEY BLOCK-----

mQENBFIUqVoBCAC7gCzgdG6NRS1vqvHFfFbQ/pkLSFvm0dgCAJcEuXys6DhptZbg
XPSPH6mEafBY/KKAgW+sH0v72mvLedUdbiwi3zU4EB3LGkUIsN8Z4EVLbIGvCcSP
DHrPVe9a+6LTD/whB/Q/Ezhfc4s4zas318WGm1ickUaMw8omms5RislLarMXapxZ
c3LcL0cjsrtviTNF+5AMNDY0gVL43TdknKXTCuRyXfOEvLKshCDtl8b0AiExtb3U
UFsqFWIXg496u/1Y/BihIHJEpTvKG7OBOWEU4bZDrPbiofmIs/Hhrs1gnPgvIhls
rHqDE3OJkqnOy99mWqiUlS0cddOwF7RgxGXxABEBAAG0NkFsYW4gUnVzYnJpZGdl
ciAoRWQpIDxhbGFuLnJ1c2JyaWRnZXJAdGhlZ3VhcmRpYW4uY29tPokBOAQTAQIA
IgUCUhSpWgIbAwYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQROYYoFdvCw05
Qwf/X5azeAiIMUgAD/N5IfPXamkmzawOPSdDr28aqFV6J25LoAJZAMCUJCHBcpkH
YdmGQUJpjT0Ru5S1FnvNrs/5dACGKANKY226Bd/H6ZVaEibQsk21sy+Vyl76h4H/
Fh5l1Rh82GuIEUM6lGVhWbh1Ms1VA7wmq4D+j9scffBoSOMm4GY0J3yjxzB1pIeI
ipGkReFxPjrKNqNQCGkihty3OoFeOwmnV7wyD5dMIJCVq1vaF/cXjqpjgS+rPYAD
H3DrFqj59B7g74KbCygxDqkH3Q1AGH8qw1vNVwdV5o3aHSQGldqWqxgOMEAg7ilV
v9YmprC65aiuRj5tl5YOyVjSaLkBDQRSFKlaAQgAwcaCKmTulHYKXh2ImwqpsYFC
KA+2BqTVWMOGdVGTN9HgIo48tI//SeUMkfh7aV55/Ab1MWljSAt3RuWU92GBrYhc
pNE3e/exhIRtsCieR0RK/7pqsyVi5rbgY1U0C4XDbzEs6P/NjZI8opcTggXL/jdI
h6M8fsi7MZYOypTbPCTXJoBe5ITsQkSt0yMAtgAFhIH7lLDmKxKcuPMRPna1+zUf
9YU6vyDKRZs2ZK2sk2VVQ2J+s1d55MPjSqR/Sl7/ADblM/pKYnrj3yKA6JouCEpF
5xFkpV39shhwfxKrTSS+KygLvnUZeRrDTAwQGKbxVq4ymqb5U3MCy6vNRY9ldQAR
AQABiQEfBBgBAgAJBQJSFKlaAhsMAAoJEETmGKBXbwsNxRkH/2R4mmKH4fOu4x8A
Rom2xbwDr3q+55WGkZTT4iEbiOFyWL6ba+hs8TOQJaZm7/DkAenrkE7ryKfbJHC7
PfqNLbBG6UC81TDBl/f4QJ9LEo0URYWBTt6O12REvOzSzJo9qF4PxL+ac1CrWaeb
6lF3DVaQb23pnL8qBlKOjm6ghrPil4y4TznudT38EaJqmVWnUlUUgxxg/eAUaxJJ
jnEldU3qSlgd062sXPqet4tnTlZNZEHIhF0oUPifoiMt6eGKvQ5/5bpscdQkN2vY
fUg9qJqAjBZq99L/hjqU09XZE30/aRSSaWMxM1ZzS82IyMZ30SJh2ZwBwVjcpBdZ
cftS/+k=
=NK7s
-----END PGP PUBLIC KEY BLOCK-----
bash-4.2$

and it works.  Nice to find an undocumented (insofar as it's not in the help screen) parameter in GnuPG.