--- a/hgext/convert/bzr.py	Sun May 17 04:33:39 2009 +0200
+++ b/hgext/convert/bzr.py	Sun May 17 14:35:06 2009 +0200
@@ -45,10 +45,31 @@
             raise NoRepo('Bazaar modules could not be loaded')
 
         path = os.path.abspath(path)
+        self._checkrepotype(path)
         self.branch = branch.Branch.open(path)
         self.sourcerepo = self.branch.repository
         self._parentids = {}
 
+    def _checkrepotype(self, path):
+        # Lightweight checkouts detection is informational but probably
+        # fragile at API level. It should not terminate the conversion.
+        try:
+            from bzrlib import bzrdir
+            dir = bzrdir.BzrDir.open_containing(path)[0]
+            try:
+                tree = dir.open_workingtree(recommend_upgrade=False)
+                branch = tree.branch
+            except (errors.NoWorkingTree, errors.NotLocalUrl), e:
+                tree = None
+                branch = dir.open_branch()
+            if (tree is not None and tree.bzrdir.root_transport.base !=
+                branch.bzrdir.root_transport.base):
+                self.ui.warn(_('warning: lightweight checkouts may cause '
+                               'conversion failures, try with a regular '
+                               'branch instead.\n'))
+        except:
+            self.ui.note(_('bzr source type could not be determined\n'))
+
     def before(self):
         """Before the conversion begins, acquire a read lock
         for all the operations that might need it. Fortunately

--- a/tests/test-convert-bzr	Sun May 17 04:33:39 2009 +0200
+++ b/tests/test-convert-bzr	Sun May 17 14:35:06 2009 +0200
@@ -34,6 +34,12 @@
 hg convert --filemap filemap source source-filemap-hg
 hg -R source-filemap-hg manifest -r tip
 
+echo '% convert from lightweight checkout'
+bzr checkout --lightweight source source-light
+hg convert source-light source-light-hg
+echo "% lightweight manifest"
+hg manifest -R source-light-hg -r tip
+
 # extract timestamps that look just like hg's {date|isodate}:
 # yyyy-mm-dd HH:MM zzzz (no seconds!)
 echo "% compare timestamps"

--- a/tests/test-convert-bzr.out	Sun May 17 04:33:39 2009 +0200
+++ b/tests/test-convert-bzr.out	Sun May 17 14:35:06 2009 +0200
@@ -35,6 +35,19 @@
 b
 d
 f
+% convert from lightweight checkout
+initializing destination source-light-hg repository
+warning: lightweight checkouts may cause conversion failures, try with a regular branch instead.
+scanning source...
+sorting...
+converting...
+1 Initial add: a, c, e
+0 rename a into b, create a, rename c into d
+% lightweight manifest
+a
+b
+d
+f
 % compare timestamps
 good: hg timestamps match bzr timestamps
 % merge