layouts: fix crash when importing hgsubversion itself (issue #402) Mercurial extensions are a bit weird: they aren't normally in sys.path, so you can't assume that "import hgsubversion" works. Luckily, Mercurial sneaks a little treat into sys.modules so that "import hgext_hgsubversion" does work. In fact, to get things working *as a Mercurial extension*, all that's needed is that trivial change to two import lines, in layouts/detect.py and layouts/standard.py. Unfortunately, hgsubversion is also imported as a Python module, in its own test suite. In that context, there is no "hgext_" trick -- unless we do it in ourselves, which I've done in TestBase.setUp(). That would work fine ... except that test_util imports from hgsubversion, which ends up importing hgsubversion.layouts.{detect,standard}, which want the "hgext_" trick to work. But it hasn't been done yet when we're still importing; it doesn't happen until setUp() runs. So make those two imports happen late, in the functions that need them. Incidentally, this is only necessary to support Mercurial <= 2.7. Mercurial got a bit smarter in 2.8: http://selenic.com/repo/hg/rev/621a26eb3a99

--- a/hgsubversion/layouts/standard.py
+++ b/hgsubversion/layouts/standard.py
@@ -2,7 +2,6 @@ import os.path
 import pickle
 
 import base
-import hgsubversion.util as util
 
 class StandardLayout(base.BaseLayout):
     """The standard trunk, branches, tags layout"""
@@ -57,6 +56,9 @@ class StandardLayout(base.BaseLayout):
         return '%s/%s' % (subdir or '', branchpath)
 
     def taglocations(self, meta_data_dir):
+        # import late to avoid trouble when running the test suite
+        from hgext_hgsubversion import util
+
         if self._tag_locations is None:
 
             tag_locations_file = os.path.join(meta_data_dir, 'tag_locations')