Git push failure with update hook success

We seem to have a few permission problems using git through ssh that we hopefully will resolve. However, in the course of this, we have noticed that our update hook runs with no errors, sends out a confirmation email, but the push to our repo fails (we found that the log file had improper permissions due to umask botchitude).

So, I surmised that the rough order of things is on our git company repo is:

o receive the git "package" from the person who is pushing it
o call the update hook, telling it the package that is coming in
o the update hook examines things, forms an email, and sends it out
o the rest of the git machinery then actually applies the changes,
  logs them, etc., but fails (after the email is long gone), and
  on the remote (client) side, the push fails.
o the user gets a confirmation email that the push went ok

So, I was wondering if this is correct (more or less) and if so whether it might be better to call the update hook after everything had actually been written, including the log file.

Bill