Minor contagious metadata corruption in exiv2

I found some contagious metadata corruption in exiv2, such that reading a file with corrupt XML namespace values in XMP data poisons all subsequent metadata writes with the same corrupt namespace — even to other files. I don’t think it is very serious (at least, compared to other data corruption bugs). All software seems to read the files just fine before and after, and the corruption is limited to XML namespace attributes. But it was interesting! I made a proof of concept that demonstrates it. How I got here I never would have found this, except that I have been testing using git-annex to store my darktable photo library. I keep the originals in git-annex, but the XMP files containing edits and metadata in regular git. After setting up git-annex, I edited a few photos, and found weird changes in git diff: Replacing http with (ttp - xmlns:xmpMM="http://ns.adobe.com/xap/1.0/mm/" + xmlns:xmpMM="(ttp://ns.adobe.com/xap/1.0/mm/" abobe, with two Bs -…