maint: examples: beware of ~/.inputrc

[Akim Demaille]

commit c3585f41efa1e5dc8ce41c800fe2963ae66c09ab
Author: Akim Demaille <address@hidden>
Date:   Sun May 10 08:20:30 2020 +0200

    examples: beware of ~/.inputrc
    
    * examples/c/bistromathic/bistromathic.test: here.

diff --git a/NEWS b/NEWS
index 21937f12..31df56c5 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,9 @@ GNU Bison NEWS
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** Bug fixes
+
+  GNU readline portability issues.
 
 * Noteworthy changes in release 3.6 (2020-05-08) [stable]
 
diff --git a/examples/c/bistromathic/README.md 
b/examples/c/bistromathic/README.md
index 05f1b7ed..6b66299e 100644
--- a/examples/c/bistromathic/README.md
+++ b/examples/c/bistromathic/README.md
@@ -14,6 +14,9 @@ This example demonstrates best practices when using Bison.
 - It supports debug traces with semantic values.
 - It uses named references instead of the traditional $1, $2, etc.
 
+To customize the interaction with bistromathic, see the GNU Readline user
+manual (see `info rluserman`).
+
 <!---
 Local Variables:
 fill-column: 76
diff --git a/examples/c/bistromathic/bistromathic.test 
b/examples/c/bistromathic/bistromathic.test
index 2ef8bc03..48b30a4c 100755
--- a/examples/c/bistromathic/bistromathic.test
+++ b/examples/c/bistromathic/bistromathic.test
@@ -15,6 +15,10 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# Users may customize the behavior of readline, which might break our
+# expected results.
+INPUTRC=/dev/null
+export INPUTRC
 
 # Beware of portability issues of readline when not feeding it from a
 # terminal.