Proof of Lemma Tag 0379

Thanks to Adeel Ahmed Khan
http://stacks.math.columbia.edu/tag/0379#comment-118
Changes to proof Lemma Tag 02R1

Thanks to Adeel Ahmed Khan
http://stacks.math.columbia.edu/tag/02R1#comment-119
http://stacks.math.columbia.edu/tag/02R1#comment-122