Fix up vec guarnatee around capacity
Fix up vec guarnatee around capacity

Fixes #37746

graydon/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust