Wrong path separator on Windows when removing a calculation through the WebUI

[ptormene]

The last slash is wrong:
Could not remove C:\Users\devops\oqdata/calc_3.hdf5: [WinError 2] The system cannot find the file specified: 'C:\\Users\\devops\\oqdata/calc_3.hdf5'
The wrong path comes from:
owner, path = db('SELECT user_name, ds_calc_dir FROM job WHERE id=?x', job_id, one=True)

[micheles]

This is a good digging exercise for you, Paolo ;-)