Fix a typo in attach_interface error path

This prevents an attach failure from raising the proper exception to
the caller.

Change-Id: I51559cf395fc99738127b7a443437197d15f3d4c
(cherry picked from commit 0ce92fcb233837f4715a173601707c6d65cf177c)
Fix _error_out_instance exception handler

Since Eventlet clears exceptions between greenthread switching, we need
to save that exception so it can be re-raised.

The _error_out_instance event handler did not wrap the quotas call with
the save_and_reraise_exception, so the original exception was lost.

Fixes bug 1163552

Change-Id: I69d28917aae1d787351cd800f8996532e5485eb2
(cherry picked from commit 25afdbbda8d56c509a4b34e0d6feeaafb2e46e5b)
Merge "Fix a typo in attach_interface error path" into stable/grizzly
Merge "Fix _error_out_instance exception handler" into stable/grizzly