Handle the case where an hour directory disappears between listing the

hours and trying to list the segments in that hour. This could happen if the
backfiller is deleting old hours.

segment_coverage/segment_coverage/main.py

@@ -192,7 +192,7 @@ class CoverageChecker(object):
 					hours = [name for name in os.listdir(path) if not name.startswith('.')]
 				except OSError as e:
 					if e.errno == errno.ENOENT:
-						self.logger.warning('{} does not exist')
+						self.logger.warning('{} does not exist'.format(path))
 						break
 
 				hours.sort()
@@ -207,7 +207,12 @@ class CoverageChecker(object):
 					# based on common.segments.best_segments_by_start
 					# but more complicated to capture more detailed metrics
 					hour_path = os.path.join(self.base_dir, self.channel, quality, hour)
+					try:
 						segment_names = [name for name in os.listdir(hour_path) if not name.startswith('.')]
+					except OSError as e:
+						if e.errno == errno.ENOENT:
+							self.logger.warning('{} does not exist'.format(hour_path))
+							break 
 					segment_names.sort()
 					parsed = []
 					bad_segment_count = 0