bitbake: cookerdata: Show a readable error for invalid multiconfig name

If a multiconfig starts with a digit, users would see pages of
errors as we use the multiconfig as a python function name prefix
and python functions cannot start with a digit. We could avoid doing
that but it is easier just to ask users to name multiconfigs not
starting with digits.

This tweak ensures the user sees an easier to understand error.

(Bitbake rev: f9cddaeef35b2ea0dadf717101ed896f6b857abd)

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

bitbake/lib/bb/cookerdata.py

@@ -291,6 +291,8 @@ class CookerDataBuilder(object):
 
             multiconfig = (self.data.getVar("BBMULTICONFIG") or "").split()
             for config in multiconfig:
+                if config[0].isdigit():
+                    bb.fatal("Multiconfig name '%s' is invalid as multiconfigs cannot start with a digit" % config)
                 mcdata = self.parseConfigurationFiles(self.prefiles, self.postfiles, config)
                 bb.event.fire(bb.event.ConfigParsed(), mcdata)
                 self.mcdata[config] = mcdata