Netbsd10_beta evbarm aarch64 userland build failure

[joelp%sdf.org@localhost]

I'm trying to build a newly sync'd RockPro64 kernel and userland:
./build.sh -U -u -j6 -O ../obj -m evbarm -a aarch64 kernel=ROCKPRO64
distribution
I can successfully build tools and the kernel (copied GENERIC64 to
ROCKPRO64). Here's the error when I try a distribution build:

obj ===> distrib/evbarm/instkernel/instkernel
clean_METALOG ===> .
--- clean_METALOG ---
clean_METALOG ===> distrib/sets
--- /lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG.sanitised ---
</lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG  
/lab/src-netbsd10/src/../obj/tooldir.NetBSD-10.0_BETA-evbarm/bin/nbawk '{
a[$1] = $0; } END { for (f in a) print a[f]; }' |   sort |
/lab/src-netbsd10/src/../obj/tooldir.NetBSD-10.0_BETA-evbarm/bin/nbmtree
-CSM -k all -R time -N /lab/src-netbsd10/src/etc 
>/lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG.new
nbmtree: .: missing directory in specification
nbmtree: failed at line 1 of the specification
*** Failed target:
/lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG.sanitised
*** Failed commands:
        <${METALOG}  ${${MKUPDATE} != "no" :? ${METALOG_REMOVE_DUPLICATES}
| :}  sort | ${TOOL_MTREE} -CSM -k all -R time -N
${NETBSDSRCDIR}/etc  >${METALOG}.new
        => </lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG  
/lab/src-netbsd10/src/../obj/tooldir.NetBSD-10.0_BETA-evbarm/bin/nbawk
'{ a[$1] = $0; } END { for (f in a) print a[f]; }' |   sort |
/lab/src-netbsd10/src/../obj/tooldir.NetBSD-10.0_BETA-evbarm/bin/nbmtree
-CSM -k all -R time -N /lab/src-netbsd10/src/etc 
>/lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG.new
        mv ${METALOG}.new ${METALOG}.sanitised
        => mv /lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG.new
/lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG.sanitised
*** [/lab/src-netbsd10/src/../obj/destdir.evbarm/METALOG.sanitised] Error
code 1
nbmake[3]: stopped in /lab/src-netbsd10/src/distrib/sets
1 error
nbmake[3]: stopped in /lab/src-netbsd10/src/distrib/sets
nbmake[2]: stopped in /lab/src-netbsd10/src

nbmake[1]: stopped in /lab/src-netbsd10/src

nbmake: stopped in /lab/src-netbsd10/src

ERROR: Failed to make distribution

*** BUILD ABORTED ***
*** BUILD ABORTED ***

I checked and ../obj/destdir.evbarm/METALOG.sanitised doesn't exist.

I'm building on the RockPro64 (recent netbsd10_beta daily), but I see the
same error on an AMD64 Netbsd93 build machine.

Thanks - Joel