release.py: use current Python executable for ./be invocation

This allow you to cut a release where your system Python is not
compatible with be.  For example:

  $ python --version
  Python 3.2.3
  $ python2.7 ./release.py 1.1.0

1 files changed, 1 insertions, 1 deletions

diff --git a/release.py b/release.py
index 7c5f51c..c9b3549 100755
--- a/release.py
+++ b/release.py
@@ -124,7 +124,7 @@ def set_vcs_name(be_dir, vcs_name='None'):
 def make_id_cache():
     """Generate .be/id-cache so users won't need to.
     """
-    invoke(['./be', 'list'])
+    invoke([sys.executable, './be', 'list'])
 
 def create_tarball(tag):
     release_name='be-%s' % tag