Inconsistent behavior in generating file link search strings

[Matt Lundin <mdl@imapmail.org>]

I am grabbing a lot of links from plain text files these days and find
that the way in which org generates search strings in file links is
inconsistent. That is, org-capture and org-insert-link behave
differently. 

1. First, org-insert-link truncates the search string. Here are the
steps to reproduce with emacs -Q:

 - Store a link in a plain text file. The value of org-stored-links is:

    org-stored-links is a variable defined in ‘org.el’.
    Its value is

    (("file:~/test.txt::Duis aute irure dolor in\nreprehenderit in voluptate velit esse cillum dolore eu fugiat nulla\npariatur." nil))

 - Insert the link in an org buffer using org-insert-link. The resulting
   link looks like this:

   [[file:~/test.txt::Duis%20aute%20irure%20dolor%20in]]

 - This seems to run counter to the advertised behavior in
   org-context-in-file-links, which says the entire region will be
   stored by default.

 - The problem is the regex on line 10333 or org.el:

         (string-match "^file:\\(.+?\\)::\\(.+\\)" link))

2. By contrast, the annotation substitution (%a) in org-capture inserts
the whole search string:

  - Take the following capture template:
   
      (setq org-capture-templates
            '(("n" "Note" entry
	           (file "~/config/test.org")
                   "* Test\n %a\n")))

  - Select the same region in a dummy file as a above and call
    org-capture, using the "n" template.

  - The org-capture snippet contains the whole search string, including
    new lines:

        * Test
         [[file:~/test.txt::Duis%20aute%20irure%20dolor%20in%0Areprehenderit%20in%20voluptate%20velit%20esse%20cillum%20dolore%20eu%20fugiat%20nulla%0Apariatur.]]
  
I think org-capture (#2) is in keeping with the behavior advertised by
org-context-in-file-links. However, as I will explain in a subsequent
bug report, org-link-search currently fails if the search string
contains new lines, so, in fact, only the one-line search strings
generated by org-insert-link actually work when following links.

Matt