Many module issues and questions seem to center on editing, testing, and deploying multiple (possibly mutually-interdependent, possibly cyclic) modules (examples: #27514, #27056, #26640, #26377).

The main workaround at the moment is to add replace directives among the modules to be edited, but maintaining those directives is tedious and error-prone. @rogpeppe's gohack tool automates away some of the tedium, but doesn't seem to remove the risk of accidentally checking in a go.mod with what were intended to be local, temporary replacements.

The go command should support multi-module edits in some form. It's not yet clear to me what form that should take, but I figured I'd go ahead and file an issue to collect ideas.

(CC: @rsc @myitcv @thepudds @marwan-at-work @oiooj @hyangah)