GHI-8735: Stale instance after auto-scaling (#143)

* GHI-8735: fail-safe server remoival in case of race condition

* GHI-8735: version bump

Author: kitherill

lib/ey-core/models/server.rb

@@ -134,7 +134,7 @@ def save!
   end
 
   def destroy!(skip_snapshot="false")
-    if environment.servers.count == 1
+    if environment.servers.reject { |server| server.id == self.id }.count == 0
       raise Ey::Core::Client::NotPermitted, "Terminating the last server in an environment is not allowed.  You must deprovision or destroy the environment instead."
     end
 

lib/ey-core/version.rb

@@ -1,5 +1,5 @@
 module Ey
   module Core
-    VERSION = "3.6.6"
+    VERSION = "3.6.7"
   end
 end