The "package" task generates the archived package which will then be 
uploaded and deleted if the "upload" task is active. If I dissociate 
both into separate tasks the "upload" task would have to guess the 
path to the generated archive. This would work in most cases but it 
doesn't seem right to me and I feel the code should ensure that it 
uploads what has just been prepared as a release.

I did add two warnings instead:

1) Exit if the user just selects the "upload" task.
2) Warn in case "package" is selected without "upload" and wait for 5 seconds.

Changes have been made in Git for this ticket:

Warn if the package/upload selection seems unusual (Bug #9698). Add a 
commit helper as option if required. Indicate when invalid tasks 
should be skipped.

  1 files changed, 19 insertions(+), 14 deletions(-)
http://git.horde.org/horde-git/-/commit/01eaa414aa702717d1edf481c9dd2ca771b34194

This is actual correct behaviour. I thought that selecting a parent 
task should automatically run all child tasks, unless those are 
specified individually too. But using that logic, it wouldn't be 
possible to run the package task *without* the upload task.
Uploading should probably be made a separate task instead of an option 
of the package task.

When running the release command with selected tasks, and one of the 
tasks is "package", then the generated package is not uploaded.
If trying to run the upload task individually, it fails too.