Unsure about buildworld

[Jeffrey Bouquet]

Used rsync to put /usr/src/.svn to
                            /usr2/src/.svn [another disk]
did an svn up of that          ^^
# sh
export CC=/usr/local/bin/clang39    # and the two others
cd /usr2/src
MAKEOBJDIRPREFIX=/usr2/obj -DNO_PROFILE ... buildworld.

................................
which halts on some error 
ranlib -d ... .a
exec(ranlib) no such file or directory
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Is there a more knowledgeable way of putting both src and obj on a seperate disk
and having the build complete AND
be sure where it builds, [ obj ] and the precise way to test an install  [ pre-rsync to the
production system , so to speak ]    or
some other *preferred* way,  extract base.txz ...   or even a clean 12.0-CURRENT snapshot
system to rsync onto the present one... 
.................................
  My motivation is I do not wish to attempt an svn upgrade of the desktop without a
certainty that the installworld will complete so the nvidia-driver can more likely
than not be restored to a working state.
............................