Fix symlinking of new projects
Fix symlinking of new projects

We weren't copying these lists, so the += was actually changing the
underlying lists.

When a new project was added to the manifest, we run _CheckDirReference
against the manifest project with share_refs=True, which added the
working_tree_* to the shareable_* lists. Then, when we load the new
manifest and create the new project, it uses the lists that already
contain the working_tree_* files, even though we passed
share_refs=False.

This happens reliably under the above conditions, but doesn't seem to
happen when syncing a fresh tree. So we've got a mixture of links that
may need to be cleaned up later. This patch will just stop it from
happening in the future.

Change-Id: Ib7935bfad78af1e494a75e55134ec829f13c2a41

mer-tools/git-repo,frogbywyplay/git-repo,codetutil/git-repo,codetutil/git-repo,11NJ/git-repo,qioixiy/git-repo,aosp-mirror/tools_repo,chzhong/git-repo,lewixliu/git-repo,wavecomp/git-repo,lewixliu/git-repo,11NJ/git-repo,lipro-yocto/git-repo,nuclearmistake/repo,qioixiy/git-repo,TheQtCompany/git-repo,GerritCodeReview/git-repo,GerritCodeReview/git-repo,wavecomp/git-repo,dodocat/git-repo,jingyu/git-repo,couchbasedeps/git-repo,gabbayo/git-repo,lipro-yocto/git-repo,gabbayo/git-repo,chzhong/git-repo,chenzilin/git-repo,testbetta/git-repo-pub,couchbasedeps/git-repo,mer-tools/git-repo,aosp-mirror/tools_repo,frogbywyplay/git-repo,TheQtCompany/git-repo,nuclearmistake/repo,dodocat/git-repo,testbetta/git-repo-pub,chenzilin/git-repo,jingyu/git-repo