Merge branch 'jc/exclude-with-gitignore' into seen

Merge branch 'jc/exclude-with-gitignore' into seen

"git add ':(exclude)foo.o'" is clearly a request not to add 'foo.o',
but the command complained about listing an ignored path foo.o on
the command line, which has been corrected.

Comments?

* jc/exclude-with-gitignore:
  dir.c: do not be fooled by :(exclude) pathspec elements