Ensure the configure script uses /bin/bash, otherwise on systems with
/bin -> /usr/bin it results in /bin/bash being embedded in various
scripts.

Index: mes/configure
===================================================================
--- mes.orig/configure
+++ mes/configure
@@ -586,7 +586,7 @@ See \"Porting GNU Mes\" in the manual, o
                      ("@V@" . ,(if disable-silent-rules? "1" "0"))
 
                      ("@AR@" . ,(or (file-name "ar" deps) ""))
-                     ("@BASH@" . ,(or (file-name "bash" deps) ""))
+                     ("@BASH@" . ,(or "/bin/bash" ""))
                      ("@CC@" . ,(or (file-name "cc" deps) ""))
                      ("@DIFF@" . ,(or (file-name "diff" deps) (string-append abs-top-builddir "/pre-inst-env diff.scm")))
                      ("@DOT@" . ,(or (file-name "dot" deps) ""))
@@ -601,8 +601,8 @@ See \"Porting GNU Mes\" in the manual, o
                      ("@PERL@" . ,(or (file-name "perl" deps) ""))
                      ("#SCHEME=\"@SCHEME@\"" . ,(if with-cheating? (string-append "\nSCHEME=\"" guile "\"") ""))
                      ("@SCHEME@" . ,(if with-cheating? guile ""))
-                     ("@SHELL@" . ,(or (file-name "bash" deps)
-                                       (file-name "sh" deps)
+                     ("@SHELL@" . ,(or "/bin/bash"
+                                       "/bin/sh"
                                        "sh"))
 
                      ("@CFLAGS@" . ,(or (getenv "CFLAGS") ""))
