// modules, the packages in the "std" module have no import-path prefix.
				//
				// Modules named "std" outside of GOROOT/src do not receive this special
				// treatment, so it is possible to run 'go test .' in other GOROOTs to
				// test individual packages using a combination of the modified package
				// and the ordinary standard library.
				// (See https://golang.org/issue/30756.)
				mainModules.pathPrefix[m] = ""
			}
		}

			work.ToolchainVersion = v
		}

		if testGOROOT := os.Getenv("TESTGO_GOROOT"); testGOROOT != "" {
			// Disallow installs to the GOROOT from which testgo was built.
			// Installs to other GOROOTs — such as one set explicitly within a test — are ok.
			work.AllowInstall = func(a *work.Action) error {
				if cfg.BuildN {
					return nil
				}

				rel := search.InDir(a.Target, testGOROOT)