vendor: fix go-iastty to not break on unknown operating systems

pup.go

@@ -16,7 +16,7 @@ import (
 //       |/ \_( # |"
 //      C/ ,--___/
 
-var VERSION string = "0.3.9"
+var VERSION string = "0.4.0"
 
 func main() {
 	// process flags and arguments

vendor/github.com/mattn/go-isatty/isatty_unsupported.go

@@ -0,0 +1,8 @@
+// +build dragonfly nacl plan9
+
+package isatty
+
+// IsTerminal return true if the file descriptor is terminal.
+func IsTerminal(fd uintptr) bool {
+	return false
+}