scripts: note to further investigate in download_blob_from_peer

Currently `lbrynet blob get <hash>` does not work to download
single blobs which are not already present in the system.
The function locks up and never returns.
It only works for blobs that are in the `blobfiles` directory
already.

This bug is reported in lbryio/lbry-sdk, issue #2070.

Maybe this script can be investigated, and certain parts
can be added to `lbry.extras.daemon.daemon.jsonrpc_blob_get`
in order to solve the previous issue, and finally download
single blobs from the network (peers or reflector servers).

scripts/download_blob_from_peer.py

@@ -1,3 +1,19 @@
+"""A simple script that attempts to directly download a single blob.
+
+To Do:
+------
+Currently `lbrynet blob get <hash>` does not work to download single blobs
+which are not already present in the system. The function locks up and
+never returns.
+It only works for blobs that are in the `blobfiles` directory already.
+
+This bug is reported in lbryio/lbry-sdk, issue #2070.
+
+Maybe this script can be investigated, and certain parts can be added to
+`lbry.extras.daemon.daemon.jsonrpc_blob_get`
+in order to solve the previous issue, and finally download single blobs
+from the network (peers or reflector servers).
+"""
 import sys
 import os
 import asyncio
@@ -47,7 +63,11 @@ async def main(blob_hash: str, url: str):
         print(f"deleted {blob_hash}")
 
 
-if __name__ == "__main__":  # usage: python download_blob_from_peer.py <blob_hash> [host url:port]
+if __name__ == "__main__":
+    if len(sys.argv) < 2:
+        print("usage: download_blob_from_peer.py <blob_hash> [host_url:port]")
+        sys.exit(1)
+
     url = 'reflector.lbry.com:5567'
     if len(sys.argv) > 2:
         url = sys.argv[2]