Parsers: remove explicit check for the retrieved folder's existence

[sphuber]

Fixes #577

As of aiida-core==1.4.0, the engine itself will check for the presence
of the retrieved folder. If it is missing, which is really just a bug in
aiida-core the engine will terminate the process and not call the
parser. Anyway there would be no point since there is nothing to parse.
This means that now if the parser is called, it is guaranteed that the
retrieve folder exists and so we no longer have to explicitly check for
it.

Since this is only valid from aiida-core>=1.4 we update the dependency
requirement. We also require aiida-core>=1.4.2 because 1.4.0 and
1.4.1 contain a bug where the content of files in local_copy_list
are copied to the repository even though they shouldn't. For this plugin
this means that mostly the content of the pseudo potentials are
duplicated everytime in the repository, which will bloat the repository
unnecessarily.

[greschd]

Hmm, I feel it's a bit early to remove 1.3 compatibility.. 1.4 is still relatively new. I may be biased though, since I haven't yet updated my production environment 😄

Anyway, maybe we could just add !=1.4.0,!=1.4.1 to the requirements now, and punt the rest of the changes for a bit? We can leave the PR as is, just put it on hold for a while.

[sphuber]

Hmm, I feel it's a bit early to remove 1.3 compatibility.. 1.4 is still relatively new.

Fair enough, but this change requires 1.4. However, it is not pressing, so we can keep it open until we feel 1.4 is stable enough

[greschd]

Alright, thanks. Did I understand it right that the current code will work fine with 1.3 and 1.4, but at 1.4 what we're removing here is essentially dead code?

And just out of curiosity: Does aiida-core also use the 300 exit code for this, or something else?

[sphuber]

Did I understand it right that the current code will work fine with 1.3 and 1.4, but at 1.4 what we're removing here is essentially dead code?

Yes

And just out of curiosity: Does aiida-core also use the 300 exit code for this, or something else?

It does define it, but it uses 100, as 1** is reserved for aiida-core internal exit codes:

https://github.com/aiidateam/aiida-core/blob/bd6903d88a4d88077150763574784a1bc375c644/aiida/engine/processes/calcjobs/calcjob.py#L197

I think it is fine, because the exit codes defined here in the plugin stem from the alpha days where I put them as a pre-caution.

[sphuber]

@greschd although this change is not really pressing, the other PR #581 to add support for aiida-pseudo is pressing, for another project we are running. This also requires aiida-core~=1.4 for the support of extras on groups. I see your point that v1.4 is still relatively young, but this will just make develop require it. We still have aiida-quantumespresso==3.2 that is compatible with lower versions. So I would argue that it is fine to make develop require v1.4.

[greschd]

Right then, let's do this. I guess if I need to use develop in production I might as well update to 1.4.2.