[c-nsp] TAC using us as a NPE-G1 bug fix test site

[Osama I Dosary]

We have about 4 NPE-G1s (both 7200 and 7301) that keep hanging. After a
few weeks of dialogue the TAC agent said they identified the bug,
another customer has it, and that they've made a debug image with a fix.
Now the TAC agent is asking us to try it. Unfortunately the only way to
try it is on production, since it needs some load. But we've already
suffered enough service disruption because of this.
When I told him such, and that we will wait until the fix is out on
mainline trains, he said that in order for the DE's (development
engineers) to apply the fix to mainline IOS we must verify that fix works.

I thought this demand strange, especially when the bug seems
reproducible, but this is my first encounter with TAC.
So I wanted to ask: Is this a reasonable demand? Is this how TAC usually
works, or just for middle east customers?

Regards,
Osama Dosary