test failure on rpi3 / armv7l

[arnetheduck]

stack trace: (most recent call last)
../eth_trie/nibbles.nim(15)
../eth_trie/nibbles.nim(12) initNibbleRange
../eth_trie/nibbles.nim(12, 27) Error: unhandled exception: value out of range
       Tip: 19 messages have been suppressed, use --verbose to show them.
     Error: nimble.nim(1115)         nimble
        ... nimble.nim(1101)         doAction
        ... nimble.nim(1075)         doAction
        ... nimble.nim(544)          execBackend
        ... tools.nim(28)            doCmd
        ... Execution failed with exit code 1
        ... Command: "/home/arnetheduck/src/Nim/bin/nim" c --noNimblePath --path:"/home/arnetheduck/.nimble/pkgs/rlp-1.0.1" --path:"/home/arnetheduck/src/nim-ranges" --path:"/home/arnetheduck/.nimble/pkgs/nimcrypto-0.3.7" --path:"/home/arnetheduck/src/nim-ranges" "--run" "--debuginfo" "--hints:off" "--path:".""  "tests/all.nim"

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