log: fix crash on empty revision with --copies switch If a revset is empty, .max() raises ValueError. I don't see any reason to recompute the revs, so I made it reuse the one returned by logcmdutil.getrevs(). If no revs specified by command line, the endrev will be smartset.spanset(repo) + 1, which is basically the same as len(repo), the default of getrenamedfn(). If --follow specified, revs.max() points to the working parent, which seems more correct.

--- a/tests/test-log.t	Tue Apr 17 21:59:58 2018 +0900
+++ b/tests/test-log.t	Fri Apr 13 23:45:07 2018 +0900
@@ -656,6 +656,9 @@
   6 
 #endif
 
+log copies, empty set
+
+  $ hg log --copies -r '0 and not 0'
 
 log -p d