This is a follow up bug to bug #6568.
Printer driver upload fails when w32x86 has not been created in upper-case on the print$ share.
It should not matter in what case this directory has been created.
Too late for enhancements for 3.5. Raising version.
*** Bug 7372 has been marked as a duplicate of this bug. ***
FYI, cupsaddsmb, which is bundled with CUPS, requires W32X86 (upper-case) for 32 bit driver installation and x64 (lower-case) for 64 bit driver installation. I noticed this when trying to add 64 bit drivers and my distro created an upper-case X64 directory (adding a symbolic link as lower-case was a usable workaround). And although Windows is case insensitive it does, with NTFS, preserve case and Windows 7, for example, has an upper-case W32X86, and a lower case x64.
I've just tested it here with master and it is working correctly again. Closing.