Fix a problem when a pull of an empty project would break it

Initial download would save "v0" as the version, then pull was
changing it to "" and afterwards push was crashing because it
was expecting "v0"

Author: wonder-sk

mergin/client_pull.py

@@ -475,7 +475,7 @@ def pull_project_finalize(job):
     conflicts = job.mp.apply_pull_changes(job.pull_changes, job.temp_dir)
     job.mp.metadata = {
         'name': job.project_path,
-        'version': job.version,
+        'version': job.version if job.version else "v0",  # for new projects server version is ""
         'files': job.project_info['files']
     }
 

mergin/test/test_client.py

@@ -364,3 +364,30 @@ def test_force_gpkg_update(mc):
     f_remote = next((f for f in project_info['files'] if f['path'] == f_updated), None)
     assert f_remote['checksum'] == updated_checksum
     assert 'diff' not in f_remote
+
+
+def test_new_project_sync(mc):
+    """ Create a new project, download it, add a file and then do sync - it should not fail """
+
+    test_project = 'test_new_project_sync'
+    project = API_USER + '/' + test_project
+    project_dir = os.path.join(TMP_DIR, test_project)  # primary project dir for updates
+
+    cleanup(mc, project, [project_dir])
+    # create remote project
+    mc.create_project(test_project)
+
+    # download the project
+    mc.download_project(project, project_dir)
+
+    # add a test file
+    shutil.copy(os.path.join(TEST_DATA_DIR, "test.txt"), project_dir)
+
+    # do a full sync - it should not fail
+    mc.pull_project(project_dir)
+    mc.push_project(project_dir)
+
+    # make sure everything is up-to-date
+    mp = MerginProject(project_dir)
+    local_changes = mp.get_push_changes()
+    assert not local_changes["added"] and not local_changes["removed"] and not local_changes["updated"]