[pdftotext] Unicode Error: Unicode character ̈(U+0308)

When using pdftotext on a pdf document including german "Umlaute" like ä, ü, ö or characters like ß the resulting text file will not include the correct unicode characters but instead ü is made to u with and additional ̈ above it.

This will create issues like with latex editors. https://tex.stackexchange.com/questions/4268/inputenc-error-unicode-char-u8-error-while-trying-to-write-a-degree-symbol

I found that using calibre to convert the same pdf document to text results in the correct characters, therefore this seems to be a bug in pdftotext