cmd/go/internal/vcweb: increase script WaitDelay by 30x

This should reduce spurious VCS failures on slow builders, like the
one observed in
https://build.golang.org/log/e773fe404b2009d67fa34f048e023f0a86663a13

Updates golang#27494.

Change-Id: Ibb094c8ddf79e0ab481c00fcf501dc955b0da787
Reviewed-on: https://go-review.googlesource.com/c/go/+/447116
Auto-Submit: Bryan Mills <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Bryan Mills <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: Bryan C. Mills

src/cmd/go/internal/vcweb/script.go

@@ -33,7 +33,7 @@ func newScriptEngine() *script.Engine {
 	conds := script.DefaultConds()
 
 	interrupt := func(cmd *exec.Cmd) error { return cmd.Process.Signal(os.Interrupt) }
-	gracePeriod := 1 * time.Second // arbitrary
+	gracePeriod := 30 * time.Second // arbitrary
 
 	cmds := script.DefaultCmds()
 	cmds["at"] = scriptAt()