ls: color each symlink-to-relative-name in / properly

In order for ls --color to color each symlink, it must form the name
of each referent and then stat it to see if the link is dangling, to
a directory, to a file, etc.  When the symlink is to a relative name,
ls must concatenate the starting directory name and that relative name.
When, in addition, the starting directory was "/" or "/some-name",
the result was ill-formed, and the subsequent stat would usually fail,
making the caller color it as a dangling symlink.
* src/ls.c (make_link_name): Don't botch the case in which
dir_name(NAME) == "/" and LINKNAME is relative.
* tests/ls/root-rel-symlink-color: New file.  Test for the above.
* tests/Makefile.am (TESTS): Add it.
* NEWS (Bug fixes): Mention it.
Reported by Mike Frysinger in http://bugs.gnu.org/11453
Bug introduced by commit v8.16-23-gbcb9078.

1 files changed, 5 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 6c620b339..f9e9c702b 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,11 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** Bug fixes
+
+  ls --color would mis-color relative-named symlinks in /
+  [bug introduced in coreutils-8.17]
+
 
 * Noteworthy changes in release 8.17 (2012-05-10) [stable]