Fix add-on store repository getting removed without internet (home-assistant#5717)

* Fix add-on store repository getting removed without internet

Currently, when a git command error happens in `pull()`, we declare
the repository as corrupt. Subsequent system autofix runs then execute
the reset resolution, which essentially removes the git repository from
the system.

In situations where the Internet fails right between the last
Supervisor connectivity check and the add-on store repository update
(the connectivity checks are throttled to once every 10 minutes while
connectivity is considered good), or if the outage is only partial
(e.g. reaching connectivity check works but the store repository is not
reachable), this leads to a git command error which declares the
repository as corrupt just as well, and ultimately leads to the removal
of the add-on store repository from the local system.

Run a git ls-remote first, which is used as an extra connectivity check.
This will also avoid removing the repository if Internet connectivity
works but the git provider is temporary down or not reachable.

That said, it will also fail if the repository is no longer present.
But this case needs extra handling anyways.

* Run git ls-remote in executor

Author: agners

supervisor/store/git.py

@@ -132,6 +132,13 @@ async def pull(self) -> bool:
         async with self.lock:
             _LOGGER.info("Update add-on %s repository from %s", self.path, self.url)
 
+            try:
+                git_cmd = git.Git()
+                await self.sys_run_in_executor(git_cmd.ls_remote, "--heads", self.url)
+            except git.CommandError as err:
+                _LOGGER.warning("Wasn't able to update %s repo: %s.", self.url, err)
+                raise StoreGitError() from err
+
             try:
                 branch = self.repo.active_branch.name