O downgrade de 1,7 para 1,6 não é possível. Por favor, encontre uma resposta aceita para esta pergunta . Por que o downgrade não é possível pode ser encontrado no script usado para fazer o downgrade. (Linha 277)
Maps format numbers to indices of fields within an entry's record that must
# be retained when downgrading to that format.
must_retain_fields = {
# Not in 1.4: changelist, keep-local, depth, tree-conflicts, file-externals
8 : (30, 31, 33, 34, 35),
# Not in 1.5: tree-conflicts, file-externals
9 : (34, 35),
10 : (),
# Downgrading from format 11 (1.7-dev) to format 10 is not possible,
# because 11 does not use has-props and cachable-props (but 10 does).
# Naively downgrading in that situation causes properties to disappear
# from the wc.
#
# Downgrading from the 1.7 SQLite-based format to format 10 is not
# implemented.
}