grep: fix --devices=ACTION (-D) so stdin is once again exempt

An oversight in the 2.11 changes made it so "echo x|grep x" would
fail for those who set GREP_OPTIONS=--devices=skip.

* src/main.c (grepdesc): Ignore skip-related options when reading
from standard input.
* tests/skip-device: New file.  Test for the above.
* tests/Makefile.am (TESTS): Add it.
* doc/grep.texi (File and Directory Selection): Clarify this point,
documenting the stdin exemption.
* NEWS (Bug fixes): Mention it, and add a few "[fixed in ...] notes.
Reported by Tino Keitel in http://bugs.debian.org/669084,
and forwarded to bug-grep by Aníbal Monsalve Salazar.

1 files changed, 6 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index b219b65e..a065394b 100644
--- a/NEWS
+++ b/NEWS
@@ -4,13 +4,17 @@ GNU grep NEWS                                    -*- outline -*-
 
 ** Bug fixes
 
+  "echo P|grep --devices=skip P" once again prints P, as it did in 2.10
+  [bug introduced in grep-2.11]
+
   grep no longer segfaults with -r --exclude-dir and no file operand.
   I.e., ":|grep -r --exclude-dir=D PAT" would segfault.
+  [bug introduced in grep-2.11]
 
   Recursive grep now uses fts for directory traversal, so it can
   handle much-larger directories without reporting things like "File
   name too long", and it can run much faster when dealing with large
-  directory hierarchies.
+  directory hierarchies. [bug present since the beginning]
 
   grep -E 'a{1000000000}' now reports an overflow error rather than
   silently acting like grep -E 'a\{1000000000}'.
@@ -27,6 +31,7 @@ GNU grep NEWS                                    -*- outline -*-
   use -R if you prefer the old behavior of following all symlinks and
   defaulting to reading all devices.
 
+
 * Noteworthy changes in release 2.11 (2012-03-02) [stable]
 
 ** Bug fixes