Push back buffer is full error

Attached PDFs result in "1.0 Syntax error, Push back buffer is full", without any further output with the latest Preflight version. Older versions don't give this error, and provide more detailed miscellaneous output. I came across this while running Preflight on a dataset of 15,000 PDFs, and quite a number seem to be affected by this.

Like https://issues.apache.org/jira/browse/PDFBOX-1812, this is something that appears to have gone wrong quite recently (possibly commit r1549022 again?), as it used to work correctly in recent October commits.

Again I included output files for both the current and the older (October) builds.