repair: copy non-revlog store files during upgrade
The store contains more than just revlogs. This patch teaches the
upgrade code to copy regular files as well.
As the test changes demonstrate, the phaseroots file is now copied.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true