bitbake: bitbake-layers: Handle exception raised bytinfoil.prepare()

The tinfoil.prepare method can raise Exceptions when is parsing initial
 data so add this call inside try, finally to avoid get blocked for
don't call tinfoil.shutdown().

The tinfoil_init function was remove because isn't make sense now since
 tinfoil.prepare() needs to be inside try, finally closures.

Example of raised exception and gets blocked:

$ bitbake-layers add-layer ~/repos/meta-openembedded/meta-python/

Traceback (most recent call last):
  File "/home/alimon/repos/poky/bitbake/bin/bitbake-layers", line 83, in
main
    tinfoil.prepare(True)
...
  File "/home/alimon/repos/poky/bitbake/lib/bb/tinfoil.py", line 268, in
run_command
    raise TinfoilCommandFailed(result[1])
bb.tinfoil.TinfoilCommandFailed: Traceback (most recent call last):
  File "/home/alimon/repos/poky/bitbake/lib/bb/command.py", line 81, in
runCommand
    result = command_method(self, commandline)
...
  File "/home/alimon/repos/poky/bitbake/lib/bb/cooker.py", line 1314, in
handleCollections
    raise CollectionError("Errors during parsing layer configuration")
bb.cooker.CollectionError: Errors during parsing layer configuration

(Bitbake rev: 61ebe9a026652e32f9482f66fc3fe7a8672fc093)

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake-layers

@@ -31,15 +31,6 @@ sys.path[0:0] = [os.path.join(topdir, 'lib')]
 
 import bb.tinfoil
 
-
-def tinfoil_init(parserecipes):
-    import bb.tinfoil
-    tinfoil = bb.tinfoil.Tinfoil(tracking=True)
-    tinfoil.prepare(not parserecipes)
-    tinfoil.logger.setLevel(logger.getEffectiveLevel())
-    return tinfoil
-
-
 def logger_create(name, output=sys.stderr):
     logger = logging.getLogger(name)
     loggerhandler = logging.StreamHandler(output)
@@ -86,8 +77,10 @@ def main():
     logger_setup_color(logger, global_args.color)
 
     plugins = []
-    tinfoil = tinfoil_init(False)
+    tinfoil = bb.tinfoil.Tinfoil(tracking=True)
+    tinfoil.logger.setLevel(logger.getEffectiveLevel())
     try:
+        tinfoil.prepare(True)
         for path in ([topdir] +
                     tinfoil.config_data.getVar('BBPATH').split(':')):
             pluginpath = os.path.join(path, 'lib', 'bblayers')