Avoid type error when local mbox lacks specified message ID

Calling b4-am with --use-local=MBOX is supposed to abort with "Could
not find MID in MBOX" if the mbox doesn't contain the specified
message ID.  As of 4950093c0 (Don't use mboxo for anything,
2021-05-18), a type error is signaled because get_strict_thread()
returns None when there are no matches, and get_msgs() feeds this
result to len().

Update get_msgs() to instead check whether the returned value
evaluates to false.

Signed-off-by: Kyle Meyer <kyle@kyleam.com>
Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Link: https://lore.kernel.org/r/20210523025812.26456-1-kyle@kyleam.com

1 files changed, 1 insertions, 1 deletions

diff --git a/b4/mbox.py b/b4/mbox.py
index a4b005f..bf1a586 100644
--- a/b4/mbox.py
+++ b/b4/mbox.py
@@ -572,7 +572,7 @@ def get_msgs(cmdargs) -> Tuple[Optional[str], Optional[list]]:
 
             if msgid:
                 msgs = b4.get_strict_thread(in_mbx, msgid)
-                if not len(msgs):
+                if not msgs:
                     logger.critical('Could not find %s in %s', msgid, cmdargs.localmbox)
                     sys.exit(1)
             else: