sftp: require go1.8+ after github.com/pkg/sftp update

backend/sftp/sftp.go

@@ -1,6 +1,6 @@
 // Package sftp provides a filesystem interface using github.com/pkg/sftp
 
-// +build !plan9
+// +build !plan9,go1.8
 
 package sftp
 

backend/sftp/sftp_internal_test.go

@@ -1,3 +1,5 @@
+// +build !plan9,go1.8
+
 package sftp
 
 import (

backend/sftp/sftp_test.go

@@ -2,6 +2,9 @@
 //
 // Automatically generated - DO NOT EDIT
 // Regenerate with: make gen_tests
+
+// +build !plan9,go1.8
+
 package sftp_test
 
 import (

backend/sftp/sftp_unsupported.go

@@ -1,6 +1,6 @@
 // Build for sftp for unsupported platforms to stop go complaining
 // about "no buildable Go source files "
 
-// +build plan9
+// +build plan9 !go1.8
 
 package sftp

backend/sftp/stringlock.go

@@ -1,3 +1,5 @@
+// +build !plan9,go1.8
+
 package sftp
 
 import "sync"

backend/sftp/stringlock_test.go

@@ -1,3 +1,5 @@
+// +build !plan9,go1.8
+
 package sftp
 
 import (