We want to allow builds in chroots that lack /bin/sh.  Thus, system(3)
and popen(3) need to be tweaked to use the right shell.  For the bootstrap
glibc, we just use whatever `sh' can be found in $PATH.  The final glibc
instead uses the hard-coded absolute file name of `bash'.

--- a/sysdeps/posix/system.c
+++ b/sysdeps/posix/system.c
@@ -134,7 +134,7 @@ do_system (const char *line)
       INIT_LOCK ();
 
       /* Exec the shell.  */
-      (void) __execve (SHELL_PATH, (char *const *) new_argv, __environ);
+      (void) __execvpe (SHELL_NAME, (char *const *) new_argv, __environ);
       _exit (127);
     }
   else if (pid < (pid_t) 0)

--- b/libio/iopopen.c	2012-06-30 21:12:34.000000000 +0200
+++ b/libio/iopopen.c	2012-12-19 12:52:29.000000000 +0100
@@ -226,7 +226,7 @@ _IO_new_proc_open (fp, command, mode)
 	    _IO_close (fd);
 	}
 
-      _IO_execl ("/bin/sh", "sh", "-c", command, (char *) 0);
+      execlp ("sh", "sh", "-c", command, (char *) 0);
       _IO__exit (127);
     }
   _IO_close (child_end);
