Workaround missing zip snapshot

At the moment, xenserver installation depends on github snapshots.
Unfortunately, git.openstack.org does not have that capability. This
fix includes:

 - Exit with error code, if a download fails
 - create proper urls, even if they are using the git protocol
 - set git base to github - so we are able to do snapshots

Fixes bug: 1259905

Change-Id: I8d0cf8bf8abb16ee0a4b138a6719409c75e7a146
diff --git a/tools/xen/test_functions.sh b/tools/xen/test_functions.sh
index 1455186..373d996 100755
--- a/tools/xen/test_functions.sh
+++ b/tools/xen/test_functions.sh
@@ -29,6 +29,9 @@
 
     XE_CALLS=$(mktemp)
     truncate -s 0 $XE_CALLS
+
+    DEAD_MESSAGES=$(mktemp)
+    truncate -s 0 $DEAD_MESSAGES
 }
 
 # Teardown
@@ -64,6 +67,10 @@
     grep -qe "^$1\$" $XE_CALLS
 }
 
+function assert_died_with {
+    diff -u <(echo "$1") $DEAD_MESSAGES
+}
+
 function mock_out {
     local FNNAME="$1"
     local OUTPUT="$2"
@@ -109,10 +116,16 @@
     grep "[ -d /usr/lib/xcp/plugins/ ]" $LIST_OF_ACTIONS
 }
 
-function test_zip_snapshot_location {
+function test_zip_snapshot_location_http {
     diff \
-    <(zip_snapshot_location "git://git.openstack.org/openstack/nova.git" "master") \
-    <(echo "git://git.openstack.org/openstack/nova/zipball/master")
+    <(zip_snapshot_location "http://github.com/openstack/nova.git" "master") \
+    <(echo "http://github.com/openstack/nova/zipball/master")
+}
+
+function test_zip_snapsot_location_git {
+    diff \
+    <(zip_snapshot_location "git://github.com/openstack/nova.git" "master") \
+    <(echo "http://github.com/openstack/nova/zipball/master")
 }
 
 function test_create_directory_for_kernels {
@@ -179,7 +192,7 @@
     local IGNORE
     IGNORE=$(. mocks && extract_remote_zipball "failurl")
 
-    assert_previous_command_failed
+    assert_died_with "Failed to download [failurl]"
 }
 
 function test_find_nova_plugins {