cutter: Dynamically pick between fast and full cuts

instead of it being per backend

cutter/cutter/main.py

@@ -397,14 +397,24 @@ class Cutter(object):
 			nonlocal upload_finished
 
 			try:
+				cut_type = upload_backend.preferred_cut_type
+				has_complex_transitions = any(transition is not None for transition in job.video_transitions)
 				if upload_backend.encoding_settings is None:
+					# this forces the issue
+					cut_type = 'fast'
+				elif has_complex_transitions or job.video_crop is not None:
+					# required to be full cut
+					cut_type = 'full'
+
+				if cut_type == 'fast':
 					self.logger.debug("No encoding settings, using fast cut")
-					if any(transition is not None for transition in job.video_transitions):
+					if has_complex_transitions:
 						raise ValueError("Fast cuts do not support complex transitions")
 					if job.video_crop is not None:
 						raise ValueError("Fast cuts do not support cropping")
 					cut = fast_cut_segments(job.segment_ranges, job.video_ranges)
 				else:
+					assert cut_type == 'full', cut_type
 					self.logger.debug("Using encoding settings for {} cut: {}".format(
 						"streamable" if upload_backend.encoding_streamable else "non-streamable",
 						upload_backend.encoding_settings,
@@ -929,10 +939,8 @@ def main(
 		else:
 			raise ValueError("Unknown upload backend type: {!r}".format(backend_type))
 		backend = backend_type(credentials, **backend_config)
-		if cut_type == 'fast':
-			# mark for fast cut by clearing encoding settings
-			backend.encoding_settings = None
-		elif cut_type != 'full':
+		backend.preferred_cut_type = cut_type
+		if cut_type not in ('fast', 'full'):
 			raise ValueError("Unknown cut type: {!r}".format(cut_type))
 		upload_locations[location] = backend
 		if backend.needs_transcode and not no_transcode_check: