Can a su exec be blocked or hung by a similar process?

Imagine we have a cron script that runs a hypothetical process under user foo.

foo@box> git pull

For whatever reason this process gets stuck/hung and freezes.

Then you run

su -c 'git --version' foo

What you experience is that this process gets stuck. And you have to kill it.

Then you kill the original process (the foo@box> git pull). After you kill the first stuck process – then a re-run of the second command works.

I saw this (with a different application to git) – but I’m trying to explain the order of unix operations (system calls) that could lead to this behaviour.

My question is: Can a su exec be blocked or hung by a similar process?