Bug #2525: Checks that it cannot connect with OpenNebula

src/onedb/onedb

@@ -37,6 +37,7 @@ $: << RUBY_LIB_LOCATION+'/onedb'
 
 require 'cli/command_parser'
 require 'onedb'
+require 'opennebula'
 
 FORCE={
     :name => "force",

src/onedb/onedb.rb

@@ -133,6 +133,8 @@ class OneDB
     # max_version is ignored for now, as this is the first onedb release.
     # May be used in next releases
     def upgrade(max_version, ops)
+        one_not_running()
+
         db_version = @backend.read_db_version
 
         if ops[:verbose]
@@ -437,6 +439,12 @@ is preserved.
         if File.exists?(LOCK_FILE)
             raise "First stop OpenNebula. Lock file found: #{LOCK_FILE}"
         end
+
+        client = OpenNebula::Client.new
+        rc = client.get_version
+        if !OpenNebula.is_error?(rc)
+            raise "OpenNebula found listening on '#{client.one_endpoint}'"
+        end
     end
 
     def pretty_print_db_version(db_version)