persistent-nodemap: respect the mmap setting when refreshing data
After writing updated data, we reload the in-memory data. However, that logic
was… wrong. We were doing file read when mmap was requested and when the
configuration was requesting to not use mmap… we were using it.
This should now be fine.
#
# Avoid interference from actual test env:
unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL