Assuming A
is the repo you want to cherry-pick from, and B
is the one you want to cherry-pick to, you can do this by adding </path/to/repo/A/>/.git/objects
to </path/to/repo/B>/.git/objects/info/alternates
. Create this alternates
files if it does not exist.
This will make repo B access all git objects from repo A, and will make cherry-pick work for you.