Direct check for key in command_lib['snippets'] dictionary

[nishakm]

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Description
The get_command_listing function checks if a specific command
name exists in the command_lib['snippets'] dictionary. Rather than
checking the return value of command_lib['snippets'].keys() we directly
check the command_lib['snippets'] dictionary to improve performance.

Implementation
Make the following change in tern/analyze/default/command_lib/command_lib.py:

 68 def get_command_listing(command_name):                                          
 69     '''Given a command name retrieve the listing if it exists'''                
 70     listing = {}                                                                
 71     if command_name in command_lib['snippets'].keys(): <-- change this to command_lib['snippets']               
 72         listing = command_lib['snippets'][command_name]                         
 73     else:                                                                       
 74         logger.warning("%s", errors.no_listing_for_snippet_key.format(          
 75             listing_key=command_name))                                          
 76     return listing     

[Samaiya]

@nishakm can you please assign this to me , I am participating in vGHC OSD event

[Samaiya]

@nishakm what is the upstream branch to use for this ?