Import shake requiring multiple passes

Stream: mathlib4

[Ruben Van de Velde]

Has anyone else noticed recently that lake exe shake takes multiple rounds of changes to pass? Just noticed it again in #18949, but also in some other changes I made recently (but I force-pushed over them)

[Yaël Dillies]

Yes, most recently it happened to me in #18917

[Kim Morrison]

Yes, I've observed this, too.

[Anne Baanen]

I needed quite a few passes in #18619 too.