fix: clarify how to break out of build_tx loops

[ibz]

Fixes #4191

[prusnak]

If you enter empty string, the condition above (if not x) will be true and perform break instead of continue, no?

[ibz]

If you enter empty string, the condition above (if not x) will be true and perform break instead of continue, no?

I think that was the original intent, indeed. But it does not seem to work for me. If you enter empty string, parse_vin will fail to parse it, and prompt will keep asking you for a new value until it receives one it can parse.

I added the continue for the case where you input an invalid value that is not "", so you will be asked for a new value and break is there to get out of the infinite loop.

[obrusvit]

related: #4144

[matejcik]

the "source distribution" is what you get when you download trezor...zip from pypi
so the paths in python/ subdir are relative to that. please revert here & below.

(the change is appropriate in tools/snippets)

[ibz]

Done. 7407bd7

[matejcik]

it seems that the fix proposed in #4191 is simpler, why not use that?

[ibz]

it seems that the fix proposed in #4191 is simpler, why not use that?

That also works, but there are 2 loops I got stuck in, and this PR addresses both.

But sure, I could change parse_vin in this case like the suggested change. But this way it is consistent.