Switch from expecting a reconnection to *not* doing do

If we're aborting mirror operations early, a couple of specs need to
change sense.

tests/acceptance/fakes/dest/reject_acl.rb

@@ -1,6 +1,7 @@
 #!/usr/bin/env ruby
 
 # Accept a connection, then immediately close it.  This simulates an ACL rejection.
+# We do not expect a reconnection.
 
 require 'flexnbd/fake_dest'
 include FlexNBD
@@ -9,6 +10,15 @@ addr, port = *ARGV
 server = FakeDest.new( addr, port )
 server.accept.close
 
+
+begin
+  server.accept
+  fail "Unexpected reconnection"
+rescue Timeout::Error
+  # expected
+end
+
 server.close
 
+
 exit(0)