Merge pull request #2217 from edbrannin/patch-1

shorten output when ImportError due to app bug.

flask/cli.py

@@ -93,7 +93,9 @@ def locate_app(app_id):
         # Reraise the ImportError if it occurred within the imported module.
         # Determine this by checking whether the trace has a depth > 1.
         if sys.exc_info()[-1].tb_next:
-            raise
+            stack_trace = traceback.format_exc()
+            raise NoAppException('There was an error trying to import'
+                    ' the app (%s):\n%s' % (module, stack_trace))
         else:
             raise NoAppException('The file/path provided (%s) does not appear'
                                  ' to exist.  Please verify the path is '

tests/test_cli.py

@@ -83,7 +83,7 @@ def test_locate_app(test_apps):
     pytest.raises(NoAppException, locate_app, "notanpp.py")
     pytest.raises(NoAppException, locate_app, "cliapp/app")
     pytest.raises(RuntimeError, locate_app, "cliapp.app:notanapp")
-    pytest.raises(ImportError, locate_app, "cliapp.importerrorapp")
+    pytest.raises(NoAppException, locate_app, "cliapp.importerrorapp")
 
 
 def test_find_default_import_path(test_apps, monkeypatch, tmpdir):