backup: Rewrite erroneously expanded SQL stmts on-the-fly

Seems to have little to no performance impact.

backup/backup.py

@@ -7,6 +7,7 @@ from urllib.parse import urlparse
 import json
 import logging
 import os
+import re
 import struct
 import sys
 import sqlite3
@@ -94,11 +95,24 @@ class Backend(object):
             f.write(snapshot)
         self.db = self._db_open(dest)
 
+    def _rewrite_stmt(self, stmt: bytes) -> bytes:
+        """We had a stmt expansion bug in c-lightning, this replicates the fix.
+
+        We were expanding statements incorrectly, missing some
+        whitespace between a param and the `WHERE` keyword. This
+        re-inserts the space.
+
+        """
+        stmt = re.sub(r'reserved_til=([0-9]+)WHERE', r'reserved_til=\1 WHERE', stmt)
+        stmt = re.sub(r'peer_id=([0-9]+)WHERE channels.id=', r'peer_id=\1 WHERE channels.id=', stmt)
+        return stmt
+
     def _restore_transaction(self, tx: Iterator[bytes]):
         assert(self.db)
         cur = self.db.cursor()
         for q in tx:
-            cur.execute(q.decode('UTF-8'))
+            q = self._rewrite_stmt(q.decode('UTF-8'))
+            cur.execute(q)
         self.db.commit()
 
     def restore(self, dest: str, remove_existing: bool = False):