Auto merge of #48576 - ishitatsuyuki:dup-fix, r=nikomatsakis
Auto merge of #48576 - ishitatsuyuki:dup-fix, r=nikomatsakis

Bring back ParamEnv deduplication

Fix #48551

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