Fixes tests for #926 and #2537

```
WARNING: MD5 of file "pdfs/issue2537.pdf" does not match file. Expected "f56805a70ed3aa52aae5c16dd335f827" computed "dc5ed0e8f3725ac12398990938bf3fcd"
```
Has some bad font

```
WARNING: File was not downloaded. See "pdfs/aboutstacks.pdf.error" file.
#926
```
2 year old, jpeg/smask. code path also tested by testissue3879.pdf or freeculture.pdf

```
WARNING: File was not downloaded. See "pdfs/issue2442.pdf.error" file.
```
just needs new node e.g. 0.10.26

(Left issue3666 and issue4436)