Hob: Fix MACHINE setting

Define the empty curr_mach to be "" instead of None.
Fix the judgement for ' if self.curr_mach == "" ' to be
' if self.curr_mach '.
Also set machine to bitbake server when "MACHINE" is not empty.

(Bitbake rev: 662fa1b126d5b9b3a80193205c22b2fe29305185)

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/ui/crumbs/builder.py

@@ -519,7 +519,7 @@ class Builder(gtk.Window):
             response = dialog.run()
             dialog.destroy()
         self.handler.clear_busy()
-        self.configuration.curr_mach = None
+        self.configuration.curr_mach = ""
         self.image_configuration_page.switch_machine_combo()
         self.switch_page(self.MACHINE_SELECTION)
 
@@ -868,7 +868,7 @@ class Builder(gtk.Window):
 
     def reparse_post_adv_settings(self):
         # DO reparse recipes
-        if self.configuration.curr_mach == "":
+        if not self.configuration.curr_mach:
             self.switch_page(self.MACHINE_SELECTION)
         else:
             self.switch_page(self.RCPPKGINFO_POPULATING)

bitbake/lib/bb/ui/crumbs/hobeventhandler.py

@@ -256,7 +256,8 @@ class HobHandler(gobject.GObject):
         self.server.runCommand(["setVariable", "BBLAYERS", " ".join(bblayers)])
 
     def set_machine(self, machine):
-        self.server.runCommand(["setVariable", "MACHINE", machine])
+        if machine:
+            self.server.runCommand(["setVariable", "MACHINE", machine])
 
     def set_sdk_machine(self, sdk_machine):
         self.server.runCommand(["setVariable", "SDKMACHINE", sdk_machine])