vend: init at unstable-2020-06-04

This is used to provide alternate vendoring for go.

pkgs/development/tools/vend/remove_tidy.patch

@@ -0,0 +1,13 @@
+diff --git a/cli/cmd.go b/cli/cmd.go
+index c766559..3a133fd 100644
+--- a/cli/cmd.go
++++ b/cli/cmd.go
+@@ -12,7 +12,7 @@ import (
+ // UpdateModule makes sure the module is updated ready to vendor the
+ // dependencies.
+ func UpdateModule() {
+-	var commands = []string{"tidy", "download", "vendor"}
++	var commands = []string{"download", "vendor"}
+ 
+ 	for _, command := range commands {
+ 		cmd := exec.Command("go", "mod", command)