Fix problems when gpg2 is installed next to gpg (#237)

* implement fixes from https://stackoverflow.com/questions/44247308/blackbox-gpg-decrypt-fails-dont-know-ctb-00
* fix problems when working with gpg2 next to gpg. Add's readme section
* fix anchor

README.md

@@ -33,6 +33,7 @@ Table of Contents
 - [Using BlackBox on Windows](#using-blackbox-on-windows)
 - [Using BlackBox without a repo](#using-blackbox-without-a-repo)
 - [Some Subversion gotchas](#some-subversion-gotchas)
+- [Using Blackbox when gpg2 is installed next to gpg](#using-blackbox-when-gpg2-is-installed-next-to-gpg)
 - [How to submit bugs or ask questions?](#how-to-submit-bugs-or-ask-questions)
 - [Developer Info](#developer-info)
 - [Alternatives](#alternatives)
@@ -704,6 +705,19 @@ The current implementation will store the blackbox in `/keyrings` at the root of
 
 This was originally written for git and supports a two-phase commit, in which `commit` is a local commit and "push" sends the change upstream to the version control server when something is registered or deregistered with the system.  The current implementation will immediately `commit` a file (to the upstream subversion server) when you execute a `blackbox_*` command.
 
+Using Blackbox when gpg2 is installed next to gpg
+=================================================
+
+In some situations, team members or automated roles need to install gpg
+2.x next to the system gpg version 1.x. to catch up with the teams gpg
+version. On Ubuntu 16. you can ```apt-get install gnupg2``` which
+installes the binary gpg2. If you want to use this gpg2 binany run every
+blackbox command with GPG=gpg2. E.g.:
+
+```
+GPG=gpg2 blackbox_postdeploy
+```
+
 How to submit bugs or ask questions?
 ====================================
 

bin/_blackbox_common.sh

@@ -184,8 +184,15 @@ function prepare_keychain() {
   # NB: We must export the keys to a format that can be imported.
   make_self_deleting_tempfile keyringasc
   export LANG="C.UTF-8"
-  $GPG --export --no-default-keyring --keyring "$(get_pubring_path)" >"$keyringasc"
-  $GPG --import "$keyringasc" 2>&1 | egrep -v 'not changed$' >&2
+
+  #if gpg2 is installed next to gpg like on ubuntu 16
+  if [[ "$GPG" != "gpg2" ]]; then
+    $GPG --export --no-default-keyring --keyring "$(get_pubring_path)" >"$keyringasc"
+    $GPG --import "$keyringasc" 2>&1 | egrep -v 'not changed$' >&2
+  else
+    $GPG --keyring "$(get_pubring_path)" --export | $GPG --import
+  fi
+
   echo '========== Importing keychain: DONE' >&2
 }