The rollback test holds the file it restores open with the sharing mode .NET
uses for a loaded assembly. Against the old File.Copy(overwrite: true) it fails
with 'the process cannot access the file because it is being used by another
process', which is the same refusal Windows gives for a loaded assembly and the
reason the rollback could never finish.
The rest pin the behaviour that was missing: recovery survives a log sink that
throws on every call, a displaced file is swept up later, a stale or absent
install assembly is recognised and both versions are read, a plain file path is
not mistaken for an assembly reference so the EF Core message keeps its own
wording, and the crash record appends to the newest Log*.log and reports the
path it used.
Co-authored-by: rmcrackan <rmcrackan@gmail.com>
