Fix typo in source_package.p

lib/webports/source_package.py

Index: lib/webports/source_package.py
diff --git a/lib/webports/source_package.py b/lib/webports/source_package.py
index cf29ccc0c85e033d4d54c05f8171b50fa839735f..58cd7a3a54d615756a9c26c56533d9a19e22b575 100644
--- a/lib/webports/source_package.py
+++ b/lib/webports/source_package.py
@@ -389,7 +389,7 @@ class SourcePackage(package.Package):
     rtn = subprocess.call(cmd, stdout=sys.stdout, stderr=sys.stderr,
                           cwd=self.root, env=env)
     if rtn != 0:
-      raise Error('Build failed: %s' % self.InfoString())
+      raise Error('Build failed: %s' % self.info_string())
 
   def download(self, force_mirror=None):
     """Download upstream sources and verify integrity."""