back-compatibility with old forcing.json format

[aekiss]

The current libaccessom2 master has breaking changes to the forcing.json format, in particular a451a7f and 467e3e2 which were made to support ERA5.

Consequently the standard ACCESS-OM2 configurations are incompatible with the latest libaccessom2 - see COSIMA/access-om2#262.

It would be much nicer to support both the old and new formats. This backwards compatibility would probably require a version number in forcing.json (which would signify the original format if absent).

[aekiss]

Runs with a standard config fail with the latest libaccessom2 70e2c46 with message

assertion failed: No forcing_product_name found in forcing config.

This assertion was added in a451a7f.

But weirdly, these configs work with 0ab7295 despite it being newer than a451a7f and 467e3e2 - see https://github.com/COSIMA/libaccessom2/commits/master

[aekiss]

Ah, I see - a451a7f and 467e3e2 were on branch 242-era5-support, which was later merged with 0ab7295.

We should fast-forward branch 242-era5-support to 70e2c46 (the current head of master), and change master to point to 0ab7295 so that current configs will work with it.

242-era5-support shouldn't be merged into master until we sort out back-compatibility, at the very least providing a script to convert old forcing.json files to the new format.

[aekiss]

I fast-forward branch 242-era5-support to 70e2c46 via

git fetch
git checkout master
git pull
git submodule update --init --recursive
git checkout 242-era5-support
git pull
git submodule update --init --recursive
git merge master
git submodule update --init --recursive
git push

(probably didn't need all the git submodule update --init --recursive)

Still need to change master to point to 0ab7295

[aekiss]

@micaeljtoliveira, @nichannah, @aidanheerdegen, @russfiedler, @penguian, just a heads-up that I'm about to reset the commit that master points to, via

git checkout master
git reset --hard 0ab7295
git push --force

so you might notice some weirdness next time you pull.

[aekiss]

master and 242-era5-support are now separate, divergent branches