make v1->v3 upgrade work with --features=bundled

--features=bundled enables -DSQLITE_DEFAULT_FOREIGN_KEYS=1, and so some
operations have to be done in the proper order.

* enable foreign key enforcement all the time, so I test this more reliably.
* reorder some parts of the v1->v3 order. foreign key enforcement is
  immediate (rather than deferred) by default. and ensure
  old_recording_playback isn't left with a dangling reference to old_recording
  at the v2 stage. Instead, wait until v3 to delete tables it depends on.

db/upgrade/mod.rs

@@ -89,6 +89,12 @@ pub fn run(args: &Args, conn: &mut rusqlite::Connection) -> Result<(), Error> {
         }
     }
 
+    // Enforce foreign keys. This is on by default with --features=bundled (as rusqlite
+    // compiles the SQLite3 amalgamation with -DSQLITE_DEFAULT_FOREIGN_KEYS=1). Ensure it's
+    // always on. Note that our foreign keys are immediate rather than deferred, so we have to
+    // be careful about the order of operations during the upgrade.
+    conn.execute("pragma foreign_keys = on", &[])?;
+
     // WAL is the preferred journal mode for normal operation; it reduces the number of syncs
     // without compromising safety.
     set_journal_mode(&conn, "wal").unwrap();

db/upgrade/v1_to_v2.rs

@@ -244,7 +244,12 @@ pub fn run(args: &super::Args, tx: &rusqlite::Transaction) -> Result<(), Error>
           old_camera cross join sample_file_dir
         where
           old_camera.sub_rtsp_path != '';
+    "#)?;
 
+    // Add the new video_sample_entry rows, before inserting the recordings referencing them.
+    fix_video_sample_entry(tx)?;
+
+    tx.execute_batch(r#"
         insert into recording
         select
           r.composite_id,
@@ -270,14 +275,6 @@ pub fn run(args: &super::Args, tx: &rusqlite::Transaction) -> Result<(), Error>
           old_recording r join recording_playback p on (r.composite_id = p.composite_id);
     "#)?;
 
-    fix_video_sample_entry(tx)?;
-
-    tx.execute_batch(r#"
-        drop table old_camera;
-        drop table old_recording;
-        drop table old_video_sample_entry;
-    "#)?;
-
     Ok(())
 }
 

db/upgrade/v2_to_v3.rs

@@ -114,6 +114,9 @@ pub fn run(_args: &super::Args, tx: &rusqlite::Transaction) -> Result<(), Error>
         from
           old_recording_playback;
         drop table old_recording_playback;
+        drop table old_recording;
+        drop table old_camera;
+        drop table old_video_sample_entry;
     "#)?;
     Ok(())
 }