The repository config was missing the [config] section, causing no mail to be sent out. Other settings were also odd; here's the old config file:

{{{
[core]
repositoryformatversion = 0
filemode = true
bare = true
sharedrepository = 1
[remote "origin"]
url = /home/fedora/jkeating/workdir/php-devel/
}}}

I removed the [remote "origin"] bit and added the usual [receive] and [hooks] sections.

I note that lua and dejavu-fonts also have the same odd repository configuration. I'll fix them up, but it would be nice to know how things got into that weird state.