+* readpipe
+
+It should be replaced to avoid tmp files and to improve portability.
+Also, as it is it does not call error () when execve fails, and
+therefore, running M4='m4 --version' bison will silently fail instead
+of:
+
+ bison: cannot run m4 --version: No such file or directory
+
+BTW: I would really like to be able to pass arguments to m4...
+
+