id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
26292	Refactor MigrationLoader.build_graph() to use more of MigrationGraph's features	Markus Holtermann	Jarek Glowacki	"The `build_graph` method on the `MigrationWriter` is rather complex and hard to understand. While talking to @jarekwg about #25945 we came to the conclusion that it would be worth to see if moving parts of that method into the `MigrationGraph` would be suitable.

General idea:
1. Add all normal migrations
1. Add all their dependencies (create dummy nodes for non-existing squashed migrations)
1. Replace the nodes in the graph when they have been replaces with suitable squashed migrations and update the dependencies accordingly
1. Ensure there are no dummy nodes left in the graph and the graph is consistent. "	Cleanup/optimization	closed	Migrations	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0