cp: give a better diagnostic for nonexistent dest/

This patch was written by Jim Meyering and myself.
* src/copy.c (copy_reg): Turn EISDIR to ENOTDIR to improve the
quality of diagnostics for commands like "cp a nosuch/".  Reported
by Марк Коренберг and Alan Curry in the thread starting at:
http://lists.gnu.org/archive/html/bug-coreutils/2010-11/msg00178.html
* THANKS: Update.
* tests/mv/trailing-slash: Add a test.

THANKS

@@ -362,6 +362,7 @@ M. P. Suzuki                        mpsuzuki@hiroshima-u.ac.jp
 Maciej Kwapulinski                  pikpok@univ.gda.pl
 Manas Garg                          manas@cygsoft.com
 Manfred Hollstein                   manfred@s-direktnet.de
+Марк Коренберг                      socketpair@gmail.com
 Marc Boucher                        marc@mbsi.ca
 Marc Haber                          mh+debian-bugs@zugschlus.de
 Marc Lehman                         schmorp@schmorp.de

src/copy.c

@@ -603,6 +603,12 @@ copy_reg (char const *src_name, char const *dst_name,
                 }
             }
         }
+
+      /* Improve quality of diagnostic when a nonexistent dst_name
+         ends in a slash and open fails with errno == EISDIR.  */
+      if (dest_desc < 0 && dest_errno == EISDIR
+          && *dst_name && dst_name[strlen (dst_name) - 1] == '/')
+        dest_errno = ENOTDIR;
     }
   else
     omitted_permissions = 0;

tests/mv/trailing-slash

@@ -50,4 +50,12 @@ done
 #touch a a2
 #mv a a2/ && fail=1
 
+# Test for a cp-specific diagnostic introduced after coreutils-8.7:
+printf '%s\n' \
+  "cp: cannot create regular file \`no-such/': Not a directory" \
+> expected-err
+touch b
+cp b no-such/ 2> err && fail=1
+compare err expected-err || fail=1
+
 Exit $fail