small fixes and dependency updates

vendor/github.com/pkg/sftp/server_plan9.go

@@ -0,0 +1,27 @@
+package sftp
+
+import (
+	"path"
+	"path/filepath"
+)
+
+func (s *Server) toLocalPath(p string) string {
+	if s.workDir != "" && !path.IsAbs(p) {
+		p = path.Join(s.workDir, p)
+	}
+
+	lp := filepath.FromSlash(p)
+
+	if path.IsAbs(p) {
+		tmp := lp[1:]
+
+		if filepath.IsAbs(tmp) {
+			// If the FromSlash without any starting slashes is absolute,
+			// then we have a filepath encoded with a prefix '/'.
+			// e.g. "/#s/boot" to "#s/boot"
+			return tmp
+		}
+	}
+
+	return lp
+}