Do not skip tests for IstanbulVM

[cburgdorf]

What was wrong?

We aren't testing Trinity against Istanbul yet.

How was it fixed?

• This builds upon Make sure eth_getStorageAt pads result to 32 byte #1403
• Wire tests up in tox/circle
• Remove skipping of Istanbul tests

To-Do

• Clean up commit history

• Add entry to the release notes

Cute Animal Picture

[veox]

randomStatetest94 is OK to be tagged SLOW, IMO:

ethereum/py-evm#1852 (comment)

(It is slow, true, but it also crashes the CI box because it consumes a lot of memory.)

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In fact, I wonder if SLOWEST_TESTS should just be imported from py-evm, and then amended with more cases (that are only run in trinity).

[cburgdorf]

@veox Thanks for chiming in!

In fact, I wonder if SLOWEST_TESTS should just be imported from py-evm

Generally a good idea I'd say but I'm not sure if it's possible as is because the tests aren't real modules (as in, they don't have a __init__.py file) so we can't import from them and if I recall correctly there is some obscure pytest reason for that.

[veox]

... so we can't import from them ...

Argh, I keep forgetting.