os.el: os-parse-date returns nil on empty strings.

diff --git a/os.el b/os.el
index 3d0d920..8a93f9f 100644 (file)
--- a/os.el
+++ b/os.el
@@ -609,7 +609,7 @@ The value returned is a list of duplicated ids."
 
 (defun os-parse-date (date)
   "Parse and return DATE as a time or nil."
-  (when date
+  (when (and (stringp date) (not (string= date "")))
     (date-to-time date)))
 
 (defun os-time-to-string (time)