serverapp: Use .absolute() instead of .resolve() for symlinks (#712)

Author: EricCousineau-TRI

jupyter_server/serverapp.py

@@ -2539,9 +2539,9 @@ def _resolve_file_to_run_and_root_dir(self):
         is configured, root_dir will be set to the parent
         directory of file_to_run.
         """
-        rootdir_abspath = pathlib.Path(self.root_dir).resolve()
+        rootdir_abspath = pathlib.Path(self.root_dir).absolute()
         file_rawpath = pathlib.Path(self.file_to_run)
-        combined_path = (rootdir_abspath / file_rawpath).resolve()
+        combined_path = (rootdir_abspath / file_rawpath).absolute()
         is_child = str(combined_path).startswith(str(rootdir_abspath))
 
         if is_child: