mount: if already mounted, unmount before new attempt

This is because if the user specifies that they want
to mount multiple times, something must be wrong. try
unmounting to reset things and then proceed.

core/commands2/mount_unix.go

@@ -98,6 +98,16 @@ baz
 			return nil, err
 		}
 
+		// check if we already have live mounts.
+		// if the user said "Mount", then there must be something wrong.
+		// so, close them and try again.
+		if node.Mounts.Ipfs != nil {
+			node.Mounts.Ipfs.Unmount()
+		}
+		if node.Mounts.Ipns != nil {
+			node.Mounts.Ipns.Unmount()
+		}
+
 		// error if we aren't running node in online mode
 		if node.Network == nil {
 			return nil, errNotOnline