arch prefix affects installation of packages

[GoogleCodeExporter]

What steps will reproduce the problem?
1. apt-cyg install fdupes
2.
3.

What is the expected output? What do you see instead?
Expected to successfully install the package fdupes.
Instead failed to download the package

What version of the product are you using? On what operating system?
0.57, windows 7 x64

Please provide any additional information below.
since now Cygwin supports both x86_64 and x86, package description is now 
prefixed with either x86_64 or x86, for example "install: 
x86_64/release/fdupes/fdupes-1.50-PR2-2.tar.bz2 49285 
af716582bdb43075a226c0dbd081f810". Because the mirror url also gets either 
x86_64 or x86 as the last part, a composed full package url would be like 
"http://mirrors.neusoft.edu.cn/cygwin/x86_64/x86_64/release/fdupes/fdupes-1.50-P
R2-3.tar.bz2", which is not correct.

Original issue reported on code.google.com by [email protected] on 1 Mar 2014 at 12:57