Bug: Determining file name of included files for ox-publish caching

[Joseph Carter Osborn <jcosborn@ucsc.edu>]

I have an org-mode document that imports sections from other org-mode
documents, like so:

#+BEGIN_QUOTE

* Part 1
#+INCLUDE: "./other.org::*Heading"
# and so on

#+END_QUOTE

I set up publishing for this document and encounter errors like this in
my *messages* buffer:

#+BEGIN_QUOTE
org-publish-cache-ctime-of-src: No such file: "/Users/jcosborn/path/to/project/“./other.org"
#+END_QUOTE

If I leave off the "::*..." component of the include I have no such
errors.  I believe the culprit is the capture in the regular expression
on ox-publish.el:1173, but I'm not sure why the bug exhibits in this
particular way with the stray quote being thrown into the string.
It seems like the regular expression should treat included org files
specially and split the string to avoid treating searches as part of the
file.

A minimal example has two org files "including.org" and "included.org",
where "included.org" has a heading "* Hello" and "including.org" just
has '#+INCLUDE: "./included.org::*Hello"'.

Then set up a trivial project like:

#+BEGIN_SRC elisp
(setq org-publish-project-alist
  '(("test"
    :base-directory "~/test/"
    :publishing-directory "~/test/"
    :publishing-function org-latex-publish-to-latex)))
#+END_SRC

and try to publish it, or run:

#+BEGIN_SRC elisp
(org-publish-cache-file-needs-publishing "including.org")
#+END_SRC

And you, too, should encounter the same error.

For now I will work around it by turning off caching, but I do like the
caching feature so I hope to be able to use it again someday.

Emacs  : GNU Emacs 25.3.1 (x86_64-apple-darwin16.7.0, NS appkit-1504.83 Version 10.12.6 (Build 16G29))
 of 2017-09-13
Package: Org mode version 9.1.6 (9.1.6-16-g86a382-elpaplus @ /Users/jcosborn/.emacs.d/elpa/org-plus-contrib-20180115/)

Thanks to the mailing list, as always, for being such an excellent
resource!