testdata: add test for get -vcs

This uses an external network dependency. Sigh.

testdata/get-vcs.txt

@@ -0,0 +1,59 @@
+# This is thame as get.txt except that we use the -vcs flag
+# on gohack get. Until we can figure out better, this requires
+# access to the network.
+
+[!net] skip
+[!exec:git] skip
+env GOPROXY=
+
+cd repo
+go get rsc.io/quote@v1.5.2
+env GOHACK=$WORK/gohack
+gohack get -vcs rsc.io/quote
+stdout '^rsc.io/quote => .*/gohack/rsc.io/quote$'
+! stderr .+
+
+# Check that the replace statement is there.
+grep -count=1 '^replace rsc\.io/quote => .*/gohack/rsc.io/quote$' go.mod
+
+# Check that it's a git repository
+exists $WORK/gohack/rsc.io/quote/.git
+
+# Check that the source files have been copied.
+grep '^' $WORK/gohack/rsc.io/quote/quote.go
+
+# Check that we can compile the command OK.
+go install example.com/repo
+
+# Hack the package a bit and check that it doesn't compile
+# any more.
+cp ../bogus.go $WORK/gohack/rsc.io/quote/bogus.go
+! go install example.com/repo
+stderr 'found packages wrong \(bogus\.go\) and quote \(quote\.go\)'
+
+# Use git to reset the package.
+cd  $WORK/gohack/rsc.io/quote
+exec git clean -xf
+
+# We should be able to compile it again.
+cd $WORK/repo
+go install
+
+-- repo/main.go --
+
+package main
+import (
+	"fmt"
+	"rsc.io/quote"
+)
+
+func main() {
+	fmt.Println(quote.Glass())
+}
+
+-- repo/go.mod --
+module example.com/repo
+
+-- bogus.go --
+
+package wrong

testdata/get.txt

@@ -11,6 +11,9 @@ grep -count=1 '^replace rsc\.io/quote => .*/gohack/rsc.io/quote$' go.mod
 # Check that the source files have been copied.
 grep '^' $WORK/gohack/rsc.io/quote/quote.go
 
+# It should not be a git repository.
+! exists $WORK/gohack/rsc.io/quote/.git
+
 # Check that we can compile the command OK.
 go install example.com/repo