identify: show nullid for empty repo

mercurial/commands.py

@@ -1441,10 +1441,10 b' def identify(ui, repo):'
     hash identifiers, followed by a "+" if there are uncommitted changes
     in the working directory, followed by a list of tags for this revision.
     """
+
     parents = [p for p in repo.dirstate.parents() if p != nullid]
     if not parents:
-        ui.write(_("unknown\n"))
-        return
+        parents = [nullid]
 
     hexfunc = ui.debugflag and hex or short
     modified, added, removed, deleted = repo.status()[:4]

tests/test-tags.out

@@ -1,4 +1,4 b''
-unknown
+000000000000 tip
 0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 0acdaf898367 tip
 tip                                0:0acdaf898367