[change-namespace] correctly shorten namespace when references have leading '::'

Reviewers: bkramer

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D29182

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@293187 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed