Fix file elements being added to more than one group - #1652

Fix file elements being added to more than one group#1652

Ckitakishi wants to merge 3 commits into

yonaskolb:masteryonaskolb/XcodeGen:masterfrom

Ckitakishi:fix-multiple-parent-groupsCkitakishi/XcodeGen:fix-multiple-parent-groupsCopy head branch name to clipboard