Prevent crash on unshelving when no changes apply to current tfs remote
Prevent crash on unshelving when no changes apply to current tfs remote

Should fix #746

guyboltonking/git-tfs,steveandpeggyb/Public,steveandpeggyb/Public,NathanLBCooper/git-tfs,kgybels/git-tfs,jeremy-sylvis-tmg/git-tfs,WolfVR/git-tfs,WolfVR/git-tfs,pmiossec/git-tfs,andyrooger/git-tfs,kgybels/git-tfs,kgybels/git-tfs,guyboltonking/git-tfs,guyboltonking/git-tfs,codemerlin/git-tfs,git-tfs/git-tfs,codemerlin/git-tfs,NathanLBCooper/git-tfs,WolfVR/git-tfs,NathanLBCooper/git-tfs,PKRoma/git-tfs,jeremy-sylvis-tmg/git-tfs,steveandpeggyb/Public,codemerlin/git-tfs,vzabavnov/git-tfs,jeremy-sylvis-tmg/git-tfs