loader-git: failure when saving git pack

Latest loader-git version got deployed and a shiny new error exists:

Sep 06 12:18:45 worker16 python3[904]: [2019-09-06 12:18:45,428: ERROR/ForkPoolWorker-9] Loading failure, updating to `partial` status
                                       Traceback (most recent call last):
                                         File "/usr/lib/python3/dist-packages/swh/loader/core/loader.py", line 873, inload
                                           self.store_data()
                                         File "/usr/lib/python3/dist-packages/swh/loader/core/loader.py", line 969, instore_data
                                           self.save_data()
                                         File "/usr/lib/python3/dist-packages/swh/loader/git/loader.py", line 337, in save_data
                                           pack_dir = self.get_save_data_path()
                                         File "/usr/lib/python3/dist-packages/swh/loader/core/loader.py", line 213, inget_save_data_path
                                           origin_url_hash = hashlib.sha1(self.origin['url']).hexdigest()
                                       TypeError: Unicode-objects must be encoded before hashing
Sep 06 12:18:45 worker16 python3[904]: [2019-09-06 12:18:45,456: INFO/ForkPoolWorker-9] Task swh.loader.git.tasks.UpdateGitRepository[40c0fe07-b7cb-4847-818a-02a257924637] succeeded in 2.1278265099972486s: {'status': 'failed'}

Probably introduced by 35992bf7

(This is within the scope of the loader-core but i only saw that error on loader-git)

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Migrated from T1987 (view on Phabricator)