Package repos come from untrusted sources, in terms of the buildserver. They
should be handled in VMs and containers as much as possible to avoid
vulnerabilities. As far as I could tell, `fdroid update` only has a single
place where it executes any VCS system: if there is .fdroid.yml present in
a package repo, then it will fetch the commit ID using git.
For better security properties, this implements a simple function to just
read the files to get that commit ID. The function that executes git to do
the same thing is relabeled "unsafe". That is used for status JSON
everywhere, but that runs on fdroiddata.git and fdroidserver.git, which are
trusted repos.
The unsafe version is also used in places where git.Repo() is needed for
other things.
There is no longer any reason for these to be intertwined.
This deliberately avoids touching some files as much as possible because
they are super tangled and due to be replaced. Those files are:
* fdroidserver/build.py
* fdroidserver/update.py
# Conflicts:
# tests/testcommon.py
# Conflicts:
# fdroidserver/btlog.py
# fdroidserver/import_subcommand.py
