std.fs.path.resolveWindows trips index-out-of-bounds for certain drive-relative paths #25703

thread 223411 panic: index out of bounds: index 0, len 0
Unwind error at address `/proc/self/exe:0x103fd3d` (unwind info unavailable), remaining frames may be incorrect
/home/ryan/Programming/zig/zig/lib/std/fs/path.zig:492:36: 0x120bf06 in compareDiskDesignators (std.zig)
            return ascii.toUpper(p1[0]) == ascii.toUpper(p2[0]);
                                   ^
/home/ryan/Programming/zig/zig/lib/std/fs/path.zig:618:65: 0x120653d in resolveWindows (std.zig)
                correct_disk_designator = compareDiskDesignators(drive_kind, dd, parsed.disk_designator);
                                                                ^
/home/ryan/Programming/zig/zig/lib/std/fs/path.zig:829:38: 0x1204a78 in testResolveWindows (std.zig)
    const actual = try resolveWindows(testing.allocator, paths);
                                     ^
/home/ryan/Programming/zig/zig/lib/std/fs/path.zig:803:27: 0x1210878 in decltest.resolveWindows (std.zig)
    try testResolveWindows(&[_][]const u8{ "c:foo", "bar" }, "C:foo\\bar");
                          ^
/home/ryan/Programming/zig/zig/lib/compiler/test_runner.zig:240:25: 0x119d650 in mainTerminal (test_runner.zig)
        if (test_fn.func()) |_| {
                        ^
/home/ryan/Programming/zig/zig/lib/compiler/test_runner.zig:69:28: 0x1196b91 in main (test_runner.zig)
        return mainTerminal();
                           ^
/home/ryan/Programming/zig/zig/lib/std/start.zig:618:22: 0x1190dd9 in callMain (std.zig)
            root.main();
                     ^
/home/ryan/Programming/zig/zig/lib/std/start.zig:232:5: 0x1190811 in _start (std.zig)
    asm volatile (switch (native_arch) {
    ^