util/managedfile: create symlink when staging files for local providers

When a local TFTPProviderDriver/HTTPProviderDriver is used, the file sync
can be skipped but the symlink creation in the server internal directory
shouldn't.

Signed-off-by: Robin van der Gracht <robin@protonic.nl>
[bst: adjust commit message to fit common style]
(cherry picked from commit eaacbb5)

Author: rvdgracht

labgrid/util/managedfile.py

@@ -67,17 +67,19 @@ def sync_to_resource(self, symlink=None):
                     self.local_path,
                     f"{self.rpath}{os.path.basename(self.local_path)}"
                 )
-
-            if symlink is not None:
-                self.logger.info("Linking")
-                try:
-                    conn.run_check(f"test ! -e {symlink} -o -L {symlink}")
-                except ExecutionError:
-                    raise ManagedFileError(f"Path {symlink} exists but is not a symlink.")
-                # use short options to be compatible with busybox
-                # --symbolic --force --no-dereference
-                conn.run_check(f"ln -sfn {self.rpath}{os.path.basename(self.local_path)} {symlink}")
-
+        else:
+            conn = sshmanager.open("localhost")
+            self.rpath = os.path.dirname(self.local_path) + "/"
+
+        if symlink is not None:
+            self.logger.info("Linking")
+            try:
+                conn.run_check(f"test ! -e {symlink} -o -L {symlink}")
+            except ExecutionError:
+                raise ManagedFileError(f"Path {symlink} exists but is not a symlink.")
+            # use short options to be compatible with busybox
+            # --symbolic --force --no-dereference
+            conn.run_check(f"ln -sfn {self.rpath}{os.path.basename(self.local_path)} {symlink}")
 
     def _on_nfs(self, conn):
         if self._on_nfs_cached is not None: