upgrade: fix handling of `.d` data file
The test did not used any `.d` file. So of course, their handling was broken
(for vfs encoding reason again). We fix the issue and update the test.
Note that some fncache issue remains with `.d` file. It will be taken care of
in the next changesets.
Differential Revision: https://phab.mercurial-scm.org/D6904
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.