All Builds Fail on Cygwin From chmod Returning an Error

Summary

For some unknown reason, the chmod has begun to fail on Cygwin. This is done after untar-ing the source files and results in all Cygwin RSB builds failing.

Steps to reproduce

Build any target on Cygwin. The generated do-build script is run with "sh -ex" which will exit on any command returning non-zero. The following shows the results of manually "sh -ex do-build ; echo $?"

+ tar_exit=0
+ cd sourceware-mirror-newlib-cygwin-7947581
+ chmod -R a+rX,g-w,o-w .
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