fix(python): improve traversal rule and description #1508

Job	Run time
build (javascript/express)	2m 11s
build (javascript/hapi)	13s
build (javascript/lang)	3m 20s
build (javascript/node)	14s
build (javascript/react)	24s
build (javascript/third_parties)	1m 57s
build (ruby/lang)	4m 10s
build (ruby/rails)	1m 38s
build (ruby/third_parties)	3m 21s
build (java/lang)	2m 59s
build (java/spring)	17s
build (java/android)	18s
build (java/third_parties)	32s
build (php/lang)	5m 3s
build (php/symfony)	53s
build (php/third_parties)	1m 5s
build (python/django)	51s
build (python/lang)	1m 55s
build (python/third_parties)	40s
build (go/lang)	59s
build (go/gosec)	2m 9s
build (go/gorilla)	14s
build (go/third_parties)	36s
	35m 59s

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