Wrong usage of "a/an" in the messages:
"string that is the id field for an pre-existing"
"build a etree.XML object filling certain"
Should be:
"string that is the id field for a pre-existing"
"build an etree.XML object filling certain"
Totally 2 occurrences in python-keystoneclient base code.
Change-Id: Icef5247672f95af87375a4a135a961aefb0a4906