Relax test of finish to not bother about unrelated connections

spec/pg/connection_spec.rb

@@ -766,12 +766,18 @@
 	end
 
 	it "doesn't leave stale server connections after finish" do
+		res = @conn.exec(%[SELECT COUNT(*) AS n FROM pg_stat_activity
+							WHERE usename IS NOT NULL AND application_name != ''])
+		# there's still the global @conn, but should be no more
+		old_count = res[0]['n']
+
 		described_class.connect(@conninfo).finish
+
 		sleep 0.5
 		res = @conn.exec(%[SELECT COUNT(*) AS n FROM pg_stat_activity
 							WHERE usename IS NOT NULL AND application_name != ''])
 		# there's still the global @conn, but should be no more
-		expect( res[0]['n'] ).to eq( '1' )
+		expect( res[0]['n'] ).to eq( old_count )
 	end
 
 	it "can retrieve it's connection parameters for the established connection" do