bitbake: cooker: Handle ImportError for websockets

Handles ImportError when creating a hash equivalence to ping the server.
This notifies user earlier with a more precise error if websockets can't
be used, and also prevents passing a known bad upstream value to the
local server

(Bitbake rev: aa80b3cfc5d16dfba13ca7fb9b78bae179ce3b74)

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/cooker.py

@@ -318,9 +318,10 @@ class BBCooker:
                     try:
                         with hashserv.create_client(upstream) as client:
                             client.ping()
-                    except ConnectionError as e:
+                    except (ConnectionError, ImportError) as e:
                         bb.warn("BB_HASHSERVE_UPSTREAM is not valid, unable to connect hash equivalence server at '%s': %s"
                                  % (upstream, repr(e)))
+                        upstream = None
 
                 self.hashservaddr = "unix://%s/hashserve.sock" % self.data.getVar("TOPDIR")
                 self.hashserv = hashserv.create_server(