I managed to reproduce this bug, unfortunately. And, even more unfortunately, it seems different from #302771 and it is NOT fixed by 3.0.14a-2...
Attached is a level 10 debug output from a session with the bug. The behaviour is what Ludovic described. "ls" seems to "hang" and the CPU and memory impact of smbclient slowly increases (thankfully, the machine I tested on has lots of resources). --
309879.log.bz2
Description: Binary data