@bcmills@seankhliao I'm not sure current issue title is precise: "cmd/go: 'go mod vendor' should not remove existing non-Go content from the vendor subdirectory"
"go mod vendor" removes everything when it comes to that conclusion without any warning. It removes both go code and other files as well like I described in #45355 .
I believe a title like
"cmd/go: 'go mod vendor' should not remove existing content from the vendor subdirectory without any warning"
describes the situation more precisely.
To be clear: my intent was for go mod to leave all files it isn't responsible for in peace. A warning would be good either way, but I don't want it to remove the Ruby files at all! It can do whatever it wants with Go files for all I care since that's its job.
If it insists on completely owning that directory, it needs to be configurable.