--- a/Allura/allura/lib/helpers.py
+++ b/Allura/allura/lib/helpers.py
@@ -268,6 +268,12 @@
 
 def ago_ts(timestamp):
     return ago(datetime.utcfromtimestamp(timestamp))
+
+def ago_string(s):
+    try:
+        return ago(parse(s, ignoretz=True))
+    except (ValueError, AttributeError):
+        return 'unknown'
 
 class DateTimeConverter(FancyValidator):