In 6e696faa "v↑ tempstorage 2.12.2 -> 5.2(ZODB5) 3-nxd(ZODB4-wc2)" we upgraded
tempstorage for ZODB5 and ZODB4-wc2, but were careful and left tempstorage,
that was being used with ZODB4, intact. However @tomo suggests that we should
also upgrade tempstorage for ZODB4 because of the loadBefore fixes and not to
further grow divergence in between ZODB4 and ZODB4-wc2:

    I understand that keeping the same version of tempstorage for ZODB 4 is to
    be on the safe side but I'd rather change it to tempstorage4-wc2 anyway. I mean
    we have a bugfix but we are afraid to apply it. Also, The less difference
    between ZODB 4 and ZODB 4-wc2 the better (everything will be more tested this way).
    ( !1009 (comment 137985) )

-> So let's do that.