MT#9121 Adjust repository key usage for usage from outside the sipwise network

When executing deployment.sh from outside the Sipwise network
it fails due to:

| --2014-09-16 16:49:04-- http://deb.sipwise.com/autobuild/680FBA8A.asc
| Resolving deb.sipwise.com (deb.sipwise.com)... 77.244.249.93, 2a00:4600:2::c0f:fee
| Connecting to deb.sipwise.com (deb.sipwise.com)|77.244.249.93|:80... connected.
| HTTP request sent, awaiting response... 403 Forbidden

Our existing sipwise.gpg file is now available at
http://deb.sipwise.com/spce/sipwise.gpg for public usage.

Change-Id: I08ca2e8c87b7133f9dc0bab59cb85875c57f065a

deployment.sh

@@ -135,6 +135,17 @@ loadNfsIpArray() {
   [ "$n" == "7" ] && return 0 || return 1
 }
 
+install_sipwise_key() {
+  wget -O /etc/apt/trusted.gpg.d/sipwise.gpg http://deb.sipwise.com/spce/sipwise.gpg
+
+  md5sum_sipwise_key_expected=32a4907a7d7aabe325395ca07c531234
+  md5sum_sipwise_key_calculated=$(md5sum /etc/apt/trusted.gpg.d/sipwise.gpg | awk '{print $1}')
+
+  if [ "$md5sum_sipwise_key_calculated" != "$md5sum_sipwise_key_expected" ] ; then
+    die "Error validating sipwise keyring for apt usage (expected: [$md5sum_sipwise_key_expected] - got: [$md5sum_sipwise_key_calculated])"
+  fi
+}
+
 # see MT#6253
 fai_upgrade() {
   upgrade=false # upgrade only if needed
@@ -160,8 +171,7 @@ fai_upgrade() {
     return 0
   fi
 
-  wget -O /tmp/680FBA8A.asc http://deb.sipwise.com/autobuild/680FBA8A.asc
-  apt-key add /tmp/680FBA8A.asc
+  install_sipwise_key
 
   # use temporary apt database for speed reasons
   local TMPDIR=$(mktemp -d)
@@ -1054,15 +1064,7 @@ $FIRMWARE_PACKAGES
 EOF
 fi
 
-# sipwise key setup
-wget -O /etc/apt/trusted.gpg.d/sipwise.gpg http://deb.sipwise.com/autobuild/sipwise.gpg
-
-md5sum_sipwise_key_expected=32a4907a7d7aabe325395ca07c531234
-md5sum_sipwise_key_calculated=$(md5sum /etc/apt/trusted.gpg.d/sipwise.gpg | awk '{print $1}')
-
-if [ "$md5sum_sipwise_key_calculated" != "$md5sum_sipwise_key_expected" ] ; then
-  die "Error validating sipwise keyring for apt usage (expected: [$md5sum_sipwise_key_expected] - got: [$md5sum_sipwise_key_calculated])"
-fi
+install_sipwise_key
 
 mkdir -p /etc/debootstrap/pre-scripts/
 cat > /etc/debootstrap/pre-scripts/install-sipwise-key.sh << EOF