bitbake: fetch2: Fix missing assignment

The assignment to True was missing from the code, well spotted Saul!

(Bitbake rev: e493fe8cb4953935f01361ffc0240e5818ebb283)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/__init__.py

@@ -642,7 +642,7 @@ def get_srcrev(d):
                 rev = rev[:10]
             if autoinc and not seenautoinc:
                 rev = "AUTOINC+" + rev
-                seenautoinc
+                seenautoinc = True
             format = format.replace(name, rev)
 
     return format