getpapers: PDF corrupt when downloaded with getpapers, O.K. when downloaded directly

I am totally new to getpapers, so this may be just a misunderstanding on my part of some of the inner workings of the ContentMine toolchain (even though it seems to be pretty straightforward…).

Here is the problem: when I use getpapers to download a paper, say with the command:

getpapers --query 'PMCID:"PMC5293196" JOURNAL:"PLOS ONE"' --outdir network-analysis -p

I get:

info: Searching using eupmc API
info: Found 1 open access results
warn: This version of getpapers wasn't built with this version of the EuPMC api in mind
warn: getpapers EuPMCVersion: 4.5.3.2 vs. 5.0.1 reported by api
Retrieving results [==============================] 100% (eta 0.0s)
info: Done collecting results
info: Saving result metadata
info: Full EUPMC result metadata written to eupmc_results.json
info: Individual EUPMC result metadata records written
info: Extracting fulltext HTML URL list (may not be available for all articles)
info: Fulltext HTML URL list written to eupmc_fulltext_html_urls.txt
info: Downloading fulltext PDF files
Downloading files [==============================] 100% (1/1) [0.0s elapsed, eta 0.0]
info: All downloads succeeded!

which looks pretty good to me (the warnings seem to be harmless in my case). Everything is there and the PDF seems to be in

PMC5293196/fulltext.pdf

However, when I try to open it in acroread, the reader tells me that the file is corrupt, that some font is missing etc. - and the paper is practically unreadable!

If I try to download it directly from the URL

http://europepmc.org/articles/PMC5293196?pdf=render

which is found in the eupmc_results.json as the download URL for this ID, all is OK and the paper is displayed with absolutely no errors…

There is indeed a difference in the MD5 sums of the two versions:

md5sum PMC5293196/fulltext.pdf 
b815dff20f24ddbb035b4bfc3743d7f5  PMC5293196/fulltext.pdf
md5sum PMC5293196.pdf
5771a39765664bedb8ad8815b7980921  PMC5293196.pdf

The latter (PMC5293196.pdf) is the ‘good’ one, downloaded directly from http://europepmc.org/articles/PMC5293196?pdf=render with curl, the former (PMC5293196/fulltext.pdf) is the ‘bad’ one downloaded by getpapers.

It is not a locale issue (seems to me), because the same happens to a user with

LANG=en_US
LC_CTYPE="en_US"
LC_NUMERIC="en_US"
LC_TIME="en_US"
LC_COLLATE=C

and to a user with a non-US locale.

I have nodejs 4.4.6 and getpapers is installed with

npm install --global getpapers
npm WARN deprecated node-uuid@1.4.7: use uuid module instead
npm WARN deprecated tough-cookie@2.2.2: ReDoS vulnerability parsing Set-Cookie https://nodesecurity.io/advisories/130
/usr/bin/getpapers -> /usr/lib/node_modules/getpapers/bin/getpapers.js
getpapers@0.4.12 /usr/lib/node_modules/getpapers
├── progress@1.1.8
├── version_compare@0.0.3
├── commander@2.7.1 (graceful-readlink@1.0.1)
├── chalk@1.0.0 (escape-string-regexp@1.0.5, ansi-styles@2.2.1, supports-color@1.3.1, strip-ansi@2.0.1, has-ansi@1.0.3)
├── mkdirp@0.5.1 (minimist@0.0.8)
├── sanitize-filename@1.6.1 (truncate-utf8-bytes@1.0.2)
├── got@2.9.2 (lowercase-keys@1.0.0, timed-out@2.0.0, prepend-http@1.0.4, object-assign@2.1.1, is-stream@1.1.0, infinity-agent@2.0.3, statuses@1.3.1, nested-error-stacks@1.0.2, read-all-stream@2.2.0, duplexify@3.5.0)
├── matched@0.4.4 (fs-exists-sync@0.1.0, is-valid-glob@0.3.0, arr-union@3.1.0, async-array-reduce@0.2.1, extend-shallow@2.0.1, has-glob@0.1.1, glob@7.1.1, lazy-cache@2.0.2, resolve-dir@0.1.1)
├── winston@1.0.2 (cycle@1.0.3, stack-trace@0.0.9, eyes@0.1.8, isstream@0.1.2, async@1.0.0, pkginfo@0.3.1, colors@1.0.3)
├── restler@3.4.0 (yaml@0.2.3, qs@1.2.0, iconv-lite@0.2.11, xml2js@0.4.0)
├── lodash@3.10.1
├── xml2js@0.4.17 (sax@1.2.2, xmlbuilder@4.2.1)
├── requestretry@1.12.0 (extend@3.0.0, when@3.7.8, request@2.80.0, lodash@4.17.4)
└── crossref@0.1.2 (got@5.1.0, request@2.65.0)

What is going on here? Can you please shed some light?