sftp: require go1.9+ after golang.org/x/crypto/ssh update

backend/sftp/sftp.go

@@ -1,6 +1,6 @@
 // Package sftp provides a filesystem interface using github.com/pkg/sftp
 
-// +build !plan9,go1.8
+// +build !plan9,go1.9
 
 package sftp
 

backend/sftp/sftp_internal_test.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.8
+// +build !plan9,go1.9
 
 package sftp
 

backend/sftp/sftp_test.go

@@ -1,6 +1,6 @@
 // Test Sftp filesystem interface
 
-// +build !plan9,go1.8
+// +build !plan9,go1.9
 
 package sftp_test
 

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 !go1.8
+// +build plan9 !go1.9
 
 package sftp

backend/sftp/stringlock.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.8
+// +build !plan9,go1.9
 
 package sftp
 

backend/sftp/stringlock_test.go

@@ -1,4 +1,4 @@
-// +build !plan9,go1.8
+// +build !plan9,go1.9
 
 package sftp