Log into http://cprince.devel.webdevel.redhat.com/cgi-bin/store and place a boxed set in your cart. Click Checkout and on the cart page, change the quantity to '-2' and click recalculate. The quantity will get changed back to 1 (as it should) but then click the Checkout button and on the next page (address verification) there will be an error message at the top stating that "Errors were detected in your last submission. They are displayed in RED." So, it appears that we are setting an error condition in the cart page and then not clearing it when the user corrects that error and continues on through the checkout process.
Fixed, error display added to cart so errors are displayed on the cart page itself, rather than being carried on to other pages.
The error message is not very helpful to the user however. I am getting "'-2' for item5485 is not numeric/integer" Should probably make this a little more user friendly and tell the user that they have entered an invalid quantity.
No problem, I've changed the error message to read: '-3' is not a valid quantity for 'Red Hat Professional Server + Free Red Hat Cap'
Looks good now. Closing out this bug.