narrow: consider empty commits to be "inside the narrow spec" for templates

It doesn't seem useful to exclude them, or harmful to include them. Users
writing log templates using outsidenarrow as a predicate might consider it
unexpected if their locally created empty drafts are treated as if they
contained something outside the clone.

Differential Revision: https://phab.mercurial-scm.org/D6414

hgext/narrow/narrowtemplates.py

@@ -37,7 +37,7 b' def outsidenarrow(context, mapping):'
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     m = repo.narrowmatch()
-    if not m.always():
+    if ctx.files() and not m.always():
         if not any(m(f) for f in ctx.files()):
             return 'outsidenarrow'
     return ''

tests/test-narrow.t

@@ -281,6 +281,10 b' Do some work in the empty clone'
   marked working directory as branch foo
   (branches are permanent and global, did you want a bookmark?)
   $ hg ci -m empty
+  $ hg log -T "{rev}: {desc} {outsidenarrow}\n"
+  2: empty 
+  1: add d5/f outsidenarrow
+  0: add d0/f outsidenarrow
   $ hg pull -q
 Can widen the empty clone
   $ hg tracked --addinclude d0