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.

mercurial/commands.py

@@ -3477,8 +3477,8 b' def log(ui, repo, *pats, **opts):'
     getrenamed = None
     if opts.get('copies'):
         endrev = None
-        if opts.get('rev'):
-            endrev = scmutil.revrange(repo, opts.get('rev')).max() + 1
+        if revs:
+            endrev = revs.max() + 1
         getrenamed = templatekw.getrenamedfn(repo, endrev=endrev)
 
     ui.pager('log')

tests/test-log.t

@@ -656,6 +656,9 b' log copies, execute bit set'
   6 
 #endif
 
+log copies, empty set
+
+  $ hg log --copies -r '0 and not 0'
 
 log -p d