style: no em-dash in test comments

tests/50-host.bats

@@ -70,7 +70,7 @@ party_rec() { printf '%s/party-%s:%s.d/roster\n' "$PARTY_SOCKET_DIR" "$USER" "$1
 @test "party close rejects bad names" {
   # Previous incarnation of this test edited HOST_USER in the roster
   # file and expected close to refuse. That's no longer the trust
-  # model — host identity is anchored on dir ownership, not file
+  # model: host identity is anchored on dir ownership, not file
   # content (commit 94befac), so editing HOST_USER is a no-op.
   # The "not the host" path now tests as: another user owns the dir,
   # which we can't fake without root. Coverage for the symlink and