DOI: encoded URLs should be supported

[koppor]

When building a DOI, strings like https://dx.doi.org/10.2307%2F1990888 should also be accepted

[stefan-kolb]

I think it is not possible to identify which parts of the DOI are escaped and which are not. Where is this a problem?

[koppor]

The DOI specifcation talks about encoding at https://www.doi.org/doi_handbook/2_Numbering.html#htmlencoding. I don't remember, where I hit the issue, but I never saw DOIs containing a real % (and not used for encoding) in the wild... Possibly, whenever the DOI is an URL (http...), decoding should be applied.