Minor tweak to allow date ranges. Double quote dance is to also let commit sequences still work. Addtional 'ignores' to trap issues with empty results due to the narrow ranges now more easily elicited.

gitstats

 	'linear_linestats': 1,
 	'project_name': '',
 	'processes': 8,
-	'start_date': ''
+	'start_date': '',
+	'end_date': '',
 }
 
 def getpipeoutput(cmds, quiet = False):
 
 def getlogrange(defaultrange = 'HEAD', end_only = True):
 	commit_range = getcommitrange(defaultrange, end_only)
+        datesel = ''
 	if len(conf['start_date']) > 0:
-		return '--since="%s" "%s"' % (conf['start_date'], commit_range)
+		datesel = '--since="%s" %s' % (conf['start_date'], datesel)
+	if len(conf['end_date']) > 0:
+		datesel = '--until="%s" %s' % (conf['end_date'], datesel)
+        if (len(datesel) > 0):
+		commit_range = '%s "%s"' % (datesel, commit_range)
 	return commit_range
 
 def getcommitrange(defaultrange = 'HEAD', end_only = False):
 		lines = getpipeoutput(['git rev-list --pretty=format:"%%at %%ai %%aN <%%aE>" %s' % getlogrange('HEAD'), 'grep -v ^commit']).split('\n')
 		for line in lines:
 			parts = line.split(' ', 4)
+                        if (len(parts) != 4):
+				print 'Warning: failed to parse line "%s"' % line
+                                continue
 			author = ''
 			try:
 				stamp = int(parts[0])
 		#Look up rev in cache and take info from cache if found
 		#If not append rev to list of rev to read from repo
 		for revline in revlines:
-			time, rev = revline.split(' ')
+			try:
+                              time, rev = revline.split(' ')
+			except ValueError:
+				print 'Warning: failed to parse line "%s"' % line
+                                continue
+ 
 			#if cache empty then add time and rev to list of new rev's
 			#otherwise try to read needed info from cache
 			if 'files_in_tree' not in self.cache.keys():