diff --git a/mercurial/testing/__init__.py b/mercurial/testing/__init__.py
--- a/mercurial/testing/__init__.py
+++ b/mercurial/testing/__init__.py
@@ -16,8 +16,10 @@
 
 def _timeout_factor():
     """return the current modification to timeout"""
-    default = int(environ.get('HGTEST_TIMEOUT_DEFAULT', 1))
+    default = int(environ.get('HGTEST_TIMEOUT_DEFAULT', 360))
     current = int(environ.get('HGTEST_TIMEOUT', default))
+    if current == 0:
+        return 1
     return current / float(default)