archive: abort on empty repository. Fixes #624.

mercurial/commands.py

@@ -133,7 +133,10 b' def archive(ui, repo, dest, **opts):'
     The default is the basename of the archive, with suffixes removed.
     '''
 
-    node = repo.changectx(opts['rev']).node()
+    ctx = repo.changectx(opts['rev'])
+    if not ctx:
+        raise util.Abort(_('repository has no revisions'))
+    node = ctx.node()
     dest = cmdutil.make_filename(repo, dest, node)
     if os.path.realpath(dest) == repo.root:
         raise util.Abort(_('repository root cannot be destination'))

tests/test-archive

@@ -67,3 +67,9 b' hg archive -r 0 -t tar rev-%r.tar'
 if [ -f rev-0.tar ]; then
     echo 'rev-0.tar created'
 fi
+
+echo '% empty repo'
+hg init ../empty
+cd ../empty
+hg archive ../test-empty
+exit 0

tests/test-archive.out

@@ -39,3 +39,5 b' test-TIP/bar'
 test-TIP/baz/bletch
 test-TIP/foo
 rev-0.tar created
+% empty repo
+abort: repository has no revisions