The following URL works: https://bugs.gentoo.org/alias/gcc-4.7 The following URL does not work: https://bugs.gentoo.org/alias/icu-50+gcc-4.7 Bug #439892 has alias "icu-50+gcc-4.7".
It works if you html encode the alias: https://bugs.gentoo.org/show_bug.cgi?id=icu-50_c%2B%2B11 works fine.