Finishing a release using Git Flow and embedded Git fails

After attempting to finish a release, I get an error:

sh.exe C:\Users\user\AppData\Local\Atlassian\SourceTree\gitflow_local\gitflow\git-flow release finish -f C:\Users\user\AppData\Local\Temp\hpf4qz1s.qob Sprint2
{{ 0 [main] grep (21684) C:\Users\user\AppData\Local\Atlassian\SourceTree\git_local\usr\bin\grep.exe: *** fatal error - cygheap base mismatch detected - 0x61299408/0xEE9408.}}
This problem is probably due to using incompatible versions of the cygwin DLL.
Search for cygwin1.dll using the Windows Start->Find/Search facility
and delete all but the most recent version. The most recent version should
reside in x:\cygwin\bin, where 'x' is the drive on which you have
installed the cygwin distribution. Rebooting is also suggested if you
are unable to find another cygwin DLL.  
fatal: Working tree contains unstaged changes. Aborting.
Completed with errors, see above.

I attempted to find cygwin1.dll but couldn't find anything.  I also attempted to reboot the system as well.