verifier: fix off-by-one for max_checkpoint

if a wallet had a tx mined in the max_checkpoint block, in certain cases
we would leave it forever in the "unverified" state and remain stuck in "synchronizing..."

Author: SomberNight

electrum/lnverifier.py

@@ -101,8 +101,8 @@ async def _verify_some_channels(self):
                 continue
             header = blockchain.read_header(block_height)
             if header is None:
-                if block_height < constants.net.max_checkpoint():
-                    await self.taskgroup.spawn(self.network.request_chunk(block_height, can_return_early=True))
+                if block_height <= constants.net.max_checkpoint():
+                    await self.taskgroup.spawn(self.interface.request_chunk(block_height, can_return_early=True))
                 continue
             self.started_verifying_channel.add(short_channel_id)
             await self.taskgroup.spawn(self.verify_channel(block_height, short_channel_id))

electrum/verifier.py

@@ -86,7 +86,7 @@ async def _request_proofs(self):
             # if it's in the checkpoint region, we still might not have the header
             header = self.blockchain.read_header(tx_height)
             if header is None:
-                if tx_height < constants.net.max_checkpoint():
+                if tx_height <= constants.net.max_checkpoint():
                     # FIXME these requests are not counted (self._requests_sent += 1)
                     await self.taskgroup.spawn(self.interface.request_chunk(tx_height, can_return_early=True))
                 continue