Xcode 7.1 (7B91b)
Source Control> History> Show Modified Files
Git diff for some files will not be displayed, stuck at boot ... (e.g. for StaticData.mm), while others will show (e.g. Info.plist )

Edit:
Such standalone Git GUI tools, such as XGit or SourceTree, display repos and are different from each other, this means that the repo itself seems normal, as Tim Bigeleisen suggested, it could be a “Xcode Git error”, anyway at present time i use an external git tool ...
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