oeqa/runexported.py: Fix exported test

With the changes introduced to test the eSDK
the runexported test failed during the execution.

This change fix runexported test in the least invasive
way, because of the release cycle.

(From OE-Core rev: da0abb9679cb1fd639859a2fdbd82101d0a81259)

Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/commands.py

@@ -18,7 +18,11 @@ from oeqa.utils import CommandError
 from oeqa.utils import ftools
 import re
 import contextlib
-import bb
+# Export test doesn't require bb
+try:
+    import bb
+except ImportError:
+    pass
 
 class Command(object):
     def __init__(self, command, bg=False, timeout=None, data=None, **options):