pdf.js submodule of 7.0.10 version points to non existing commit

[k-jell]

Using the 7.0.10 zotero tag, the pdf.js submodule of reader points to an invalid commit:

fatal: git upload-pack: not our ref 820effc79cef3d15e636e16bdfc0d17647c799be
fatal: remote error: upload-pack: not our ref 820effc79cef3d15e636e16bdfc0d17647c799be
fatal: Fetched in submodule path 'pdfjs/pdf.js', but it did not contain 820effc79cef3d15e636e16bdfc0d17647c799be. Direct fetching of that commit failed.

[mrtcode]

It happens when we update our pdf.js fork.

You can work around it by doing this:

cd pdfjs/pdf.js
git fetch origin 820effc79cef3d15e636e16bdfc0d17647c799be
git checkout 820effc79cef3d15e636e16bdfc0d17647c799be