job_process: Don't stop tracing processes on exec

Currently the "expect daemon" stanza is interpreted as tracing a job
until it has forked twice *or* until it has forked once and
execed. This is contrary to the documentation, and also blocks one use
for this stanza: jobs which require two nested minijail invocations to
set up. For example, seneschal uses this pattern to get around
issues with the order minijail sets up its jails.

It looks like no one is currently using this stanza in Chrome OS, so
it should be safe to correct this.

BUG=chromium:1240118
TEST=Manually tested

Change-Id: I39d68002bb90e0e06ad0017b68740989f370bf98
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/upstart/+/3097231
Reviewed-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>
Tested-by: Fergus Dall <sidereal@google.com>
Commit-Queue: Fergus Dall <sidereal@google.com>
1 file changed