Unverified blocks cap not working properly

[tomaka]

There exists a cap to the number of unverified blocks:

smoldot/src/sync/all_forks.rs

Line 1391 in 62ff6b7

while self.inner.inner.inner.blocks.num_unverified_blocks() >= 100 {

Once this cap is reached, the syncing stalls. It shouldn't.

I believe that the issue is that unverified blocks removes too much information, and the state machine isn't capable of downloading back the next block.

When I commented out this block of code, the syncing didn't stall:

smoldot/src/sync/all_forks.rs

Lines 1405 to 1409 in 62ff6b7

	self.inner
	.inner
	.inner
	.blocks
	.remove_sources_known_block(height, &hash);

[tomaka]

After #2801, we should write a test to make sure it's fixed/working.