Issue:
win10 installation git fatal: open /dev/null or dup failed: No such file or directory
Based on community feedback, the cause appears to be a problem with the null.sys driver file, which is not a plug-and-play driver. One solution proved to work.
Download the following file and replace the one in this directory:
C:/Windows/System32/drivers
Download link:
http://mirror.xrk.org/dll/null_for_win10.zip