annotate: handle empty files earlier

Rather than looping on funcmap and then checking for non-zero `l`
continue if the result of fctx.annotate is empty.

mercurial/commands.py

@@ -469,12 +469,13 b' def annotate(ui, repo, *pats, **opts):'
 
         lines = fctx.annotate(follow=follow, linenumber=linenumber,
                               diffopts=diffopts)
+        if not lines:
+            continue
         formats = []
         pieces = []
 
         for f, sep in funcmap:
             l = [f(n) for n, dummy in lines]
-            if l:
                 if fm:
                     formats.append(['%s' for x in l])
                 else:
@@ -488,7 +489,7 b' def annotate(ui, repo, *pats, **opts):'
             fm.write(fields, "".join(f), *p)
             fm.write('line', ": %s", l[1])
 
-        if lines and not lines[-1][1].endswith('\n'):
+        if not lines[-1][1].endswith('\n'):
             fm.plain('\n')
 
     fm.end()