bootable USB macOS sierra - not a valid volume mount point

the basic technique of using

/Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia to create a USB installer drive fails with error

"not a valid volume mount point"

Simple work around is to modify one string inside a file inside the macOS Sierra.app

sudo plutil -replace CFBundleShortVersionString -string "12.6.03" /Applications/Install\ macOS\ Sierra.app/Contents/Info.plist

I did it manually by going into app and opening info.plist with textedit.

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credit to

https://forums.macrumors.com/threads/not-a-valid-volume-mount-point-cant-make-bootable-drive.1935673/page-3?post=28197924#post-28197924