Bug?: git archive exclude pathspec and gitattributes export-ignore

[David Adam <zanchey@xxxxxxxxxxxxxxxxx>]

Hi all,

I think I have a bug in git (tested 2.11.0 on Debian 8, 2.14.1 on OS X and 
2.14.1.145.gb3622a4 on OS X).

Given a repository with an export-ignore directive for a subdirectory in 
.gitattributes, `git archive` with a pathspec that excludes a different 
subdirectory produces no output file and git exits with -1 as the return 
status.

As shown:

   > git init foo && cd foo
   Initialized empty Git repository in /Users/david/src/foo/.git/
   > mkdir a b
   > touch {a,b}/somefile
   > echo "/a export-ignore" >> .gitattributes
   > git add .
   > git commit -m "Initial commit"
   [master (root-commit) 53527a7] Initial commit
    3 files changed, 1 insertion(+)
    create mode 100644 .gitattributes
    create mode 100644 a/somefile
    create mode 100644 b/somefile
   > git archive --verbose master ':(top)' ':(exclude)b*'
   .gitattributes
   > echo $?
   255

If this is intended behaviour, is there any way of achieving the goal of 
excluding a subdirectory not listed as export-ignore? Using the exclude 
pathspec ":(exclude)b" produces an empty subdirectory b in the output, 
which I would like to avoid.

This is a reduced testcase; my goal is to end up with two archives, one 
containing directory b only, and one containing everything except for 
directory b - so I can't just add 'b export-ignore' to gitattributes.

Thanks

David Adam
zanchey@xxxxxxxxxxxxxxxxx