procutil: move stdin assignment outside of try-finally block
There is an stdin variable in the global scope of this module. And in the
`finally` block of this try-finally statement we're checking `if stdin is not
None`. Let's make sure we don't confuse code check tools into thinking we want
to use global stdin by moving this line of code outside of `try`.
This was caught by pytype 2023.11.21 on Python 3.11.2.
edition = "2018"
max_width = 79
wrap_comments = true
error_on_line_overflow = true