ebook-convert does not support conversion of doc -> pdf. It supports docx, not doc.

Polyglot put "doc" as one of the supported format for ebook-convert, so it puts "doc->pdf" conversion requests in ebook-convert queue, but the conversion fails to generate the PDF file.

Noticed while debugging software servers running ebook-convert, in the log it downloaded the "*.doc" file fine, but showed that the generated file had 0 B.

References:
http://manual.calibre-ebook.com/conversion.html (search for "Convert Microsoft Word documents" and "Older .doc files")
http://stackoverflow.com/questions/24868763/no-plugin-to-handle-input-format-doc-calibre
https://bugs.launchpad.net/calibre/+bug/1206099

Software server log:

[Thu Sep 17 16:06:51 2015] [rabbitm] [200453393]: Consuming job-200453393, http:
//141.142.227.81:8184/file/FTv6.doc->pdf via ebook-conver
t
[Thu Sep 17 16:06:51 2015] [rabbitm] [200453393]: API call, http://localhost:818
2/software/ebook-convert/convert/pdf/http%3A%2F%2F141
.142.227.81%3A8184%2Ffile%2FFTv6.doc
[Thu Sep 17 16:06:51 2015] [restlet] [66]: Setting session to session-66, result
will be at ESC[94mhttp://141.142.204.151:8182/file/66_FTv6.pdfESC[0m
[Thu Sep 17 16:06:51 2015] [restlet] [66]: Downloading ESC[94mhttp://141.142.227.81:8184/file/FTv6.docESC[0m (583.5 KB) ...
.
[Thu Sep 17 16:06:51 2015] [sserver] [66]: Executing, scripts/sh/ebook-convert_c
onvert.sh /home/polyglot/polyglot/tmp/SoftwareServer/Cache/66_FTv6.doc /home/pol
yglot/polyglot/tmp/SoftwareServer/Cache/66_FTv6.pdf /home/polyglot/polyglot/tmp/
SoftwareServer/Temp/66_1442524011518_ .....
[Thu Sep 17 16:06:52 2015] [sserver] [66]: Killing, scripts/sh/ebook-convert_con
vert.sh /home/polyglot/polyglot/tmp/SoftwareServer/Cache/66_FTv6.doc /home/polyg
lot/polyglot/tmp/SoftwareServer/Cache/66_FTv6.pdf /home/polyglot/polyglot/tmp/So
ftwareServer/Temp/66_1442524011518_ ...
[Thu Sep 17 16:06:52 2015] [restlet] [66]: Execution complete, result at ESC[94m/home/polyglot/polyglot/tmp/SoftwareServer/Cache/66_FTv6.pdfESC[0m (0 B)
[Thu Sep 17 16:06:52 2015] [restlet] [66]: Copied result to public folder