Read a filesystem that could not be named as unknown, never as a move (hq ADR 0325 sixth review)

A name read that timed out gave an empty name, which differed from the recorded one
and so reset the record: a folder kept while empty asked again, a warranted one was
walked again. An unnamed filesystem now leaves the folder exactly as it is, the
access is said not known for that look, and it resumes once it is named.

internal/apply/keeper_linux.go

@@ -179,6 +179,8 @@ func reconcileOne(ctx context.Context, path string, f store.KeptFolder) []string
 			why = pathless(v.err)
 		case v.kind == folderRoot:
 			why = RootWords(v.why)
+		case v.kind == folderUnknown:
+			why = v.why
 		case v.moved || v.kind == folderWaitKeep:
 			why = "what is at it now is not what the mesh kept there"
 		}