fix integrity and workspaces url

.prettierignore

@@ -23,6 +23,7 @@ jupyterlab/staging/yarn.js
 jupyterlab/staging/index.js
 packages/ui-components/src/icon/iconimports.ts
 packages/extensionmanager/examples/listings
+tsconfigdoc.json
 
 # jetbrains IDE stuff
 .idea/

jupyterlab/labapp.py

@@ -314,7 +314,7 @@ class LabWorkspaceImportApp(JupyterApp):
         base_url = '/'
         directory = app.workspaces_dir
         app_url = app.app_url
-        workspaces_url = app.workspaces_url
+        workspaces_url = ujoin(app.app_url, 'workspaces')
 
         if len(self.extra_args) != 1:
             print('One argument is required for workspace import.')