While I was playing with the yahoo pipes, the following warning popup appeared :

The same warning was presented to me at many different places.
Being an old Debian user, I realized that the problem was with my Iceweasel, the Debian way Firefox, (see the history at Wikipedia) and I had to do something manually to correct the problem.
After some google search, the simple solution to overcome the problem, was found at kmandla.wordpress.com (rephrased a little for clarity):
I needed to follow these steps
- Open a page or tab in Iceweasel, write “about:config” in the address bar and press Enter
- In the Filter box write “agent” and wait for the selections to appear
- Double-click the line with Preference Name general.useragent.extra.firefox
- Replace the word “Iceweasel” with “Firefox” and press OK
- Close the page or tab
and everything was OK and the only thing I had to do was to reload the pipe editor.
Because Iceweasel 3 was installed, after step 1, l was presented with this annoying warning:

I unchecked the “Show this warning next time”, pressed the button and proceed.