Prefix builds failing in stage 3 on python and bash

[anjames]

Following the bootstrap instructions https://wiki.gentoo.org/wiki/Project:Prefix
my builds were dieing in the python build with "recipe for target 'sharedmods' failed". I found discussion that this is caused by the latest readline (https://forums.gentoo.org/viewtopic-p-7509398.html) so added it to package.mask by patching bootstrap_prefix.sh (https://gist.github.com/anonymous/6d139bab9effadb02ab3) and now it's failing at bash build:

I put these outputs into a gist https://gist.github.com/anonymous/d0cbe23479779a965f91
* stage3.log
* emerge --info '=app-shells/bash-4.3_p39::gentoo_prefix'
* emerge -pqv '=app-shells/bash-4.3_p39::gentoo_prefix'

There don't seem to be any obvious failures in the stage3.log, so I'm at a loss for why it died. Any thoughts?

[anjames]

Looking further at this, it seems to be failing at bashline:

[anjames]

And also the last line immediately prior to the bash merge was:
>>> sys-libs/readline-6.2_p1-r1 merged.

[honp]

I have the same problem...