self-hosted compiler does not map 'std' into every package

[andrewrk]

test.zig

const bar = @import("bar");
pub fn main() void {
    _ = bar;
}

bar.zig

const std = @import("std");

comptime {
    _ = std;
}

Actual Output

$ ./zig-out/bin/zig build-exe test.zig --pkg-begin bar bar.zig --pkg-end
bar.zig:1:21: error: unable to open 'std': PackageNotFound
const std = @import("std");
                    ^

Expected Output

It should succeed the build. 'builtin' and 'root' should additionally be mapped into every package.