Ran under python 3.7 and with a local folder /tmp/sync-test and a remote folder (on device) /sdcare/sync-test.

It broken for the file with spaces in the name. The filename with full path is:
/tmp/sync-test/GitHub - google_adb-sync.mhtml

Here is the command and output.

$ python3.7 ./adb-sync -2 /tmp/sync-test /sdcard
INFO:root:Sync: local b'/tmp/sync-test', remote b'/sdcard/sync-test'
INFO:root:Scanning and diffing...
INFO:root:Push: b'/sdcard/sync-test/GitHub - google_adb-sync.mhtml'
4380 KB/s (1317055 bytes in 0.293s)
INFO:root:Pull: b'/tmp/sync-test/GitHub\ -\ google_adb-sync.mhtml'
remote object '/sdcard/sync-test/GitHub\ -\ google_adb-sync.mhtml' does not exist
INFO:root:Interrupted-Pull-Delete: b'/tmp/sync-test/GitHub\ -\ google_adb-sync.mhtml'
INFO:root:Total: 1653 KB/s (1317055 bytes in 0.778s)
Traceback (most recent call last):
File "./adb-sync", line 638, in PerformCopies
self.copy[i](src_name, dst_name)
File "./adb-sync", line 336, in Pull
raise OSError('pull failed')
OSError: pull failed