log: fix behavior with empty repositories (issue3497)

Make output in this special case consistent with general case one.

mercurial/cmdutil.py

@@ -1022,8 +1022,6 b' def walkchangerevs(repo, match, opts, pr'
 
     follow = opts.get('follow') or opts.get('follow_first')
 
-    if not len(repo):
-        return []
     if opts.get('rev'):
         revs = scmutil.revrange(repo, opts.get('rev'))
     elif follow:

mercurial/revlog.py

@@ -771,6 +771,10 b' class revlog(object):'
                 nl = [n for n in nl if hex(n).startswith(id)]
                 if len(nl) > 0:
                     if len(nl) == 1:
+                        if nl[0] == nullid:
+                            # dummy null revision always exists,
+                            # it shouldn't be returned here
+                            return None
                         self._pcache[id] = nl[0]
                         return nl[0]
                     raise LookupError(id, self.indexfile,

mercurial/revset.py

@@ -238,12 +238,10 b' def rangeset(repo, subset, x, y):'
     return [x for x in r if x in s]
 
 def dagrange(repo, subset, x, y):
-    if subset:
-        r = list(repo)
-        xs = _revsbetween(repo, getset(repo, r, x), getset(repo, r, y))
-        s = set(subset)
-        return [r for r in xs if r in s]
-    return []
+    r = list(repo)
+    xs = _revsbetween(repo, getset(repo, r, x), getset(repo, r, y))
+    s = set(subset)
+    return [r for r in xs if r in s]
 
 def andset(repo, subset, x, y):
     return getset(repo, getset(repo, subset, x), y)

tests/test-alias.t

@@ -267,10 +267,13 b' shell aliases with global options'
   $ hg init sub
   $ cd sub
   $ hg count 'branch(default)'
+  abort: unknown revision 'default'!
   0
   $ hg -v count 'branch(default)'
+  abort: unknown revision 'default'!
   0
   $ hg -R .. count 'branch(default)'
+  abort: unknown revision 'default'!
   0
   $ hg --cwd .. count 'branch(default)'
   2

tests/test-glog.t

@@ -1542,6 +1542,7 b' have 2 filelog topological heads in a li'
   $ testlog --follow
   []
   []
+  abort: unknown revision '0'!
   $ echo a > a
   $ echo aa > aa
   $ echo f > f

tests/test-log.t

@@ -1,3 +1,20 b''
+Log on empty repository: checking consistency
+
+  $ hg init empty
+  $ cd empty
+  $ hg log
+  $ hg log -r 1
+  abort: unknown revision '1'!
+  [255]
+  $ hg log -r -1:0
+  abort: unknown revision '-1'!
+  [255]
+  $ hg log -r 'branch(name)'
+  abort: unknown revision 'name'!
+  [255]
+  $ hg log -r null -q
+  -1:000000000000
+
 The g is crafted to have 2 filelog topological heads in a linear
 changeset graph