deb: make sure to have the right apt keyrings

src/deb/ephemeral.rs

@@ -120,6 +120,11 @@ impl EphemeralContextGuard {
             .arg(lockfile_path.to_string_lossy().to_string())
             .status()?;
 
+        // Make sure we have the right apt keyrings to mmdebstrap the chroot
+        tokio::runtime::Runtime::new().unwrap().block_on(
+            crate::apt::keyring::download_trust_keyring(Some(ctx.clone()), series),
+        )?;
+
         // Use mmdebstrap to download the tarball to the cache directory
         let status = ctx
             .command("mmdebstrap")