Fix the lookup of the executable in: jbuilder exec

CHANGES.org

@@ -22,6 +22,10 @@
   the jbuilder invocation in opam files and make it more future proof
   (#52)
 
+- Fix the lookup of the executable in =jbuilder exec foo=. Before,
+  even if =foo= was to be installed, the freshly built version wasn't
+  selected
+
 * 1.0+beta6 (29/03/2017)
 
 - Add an =(executable ...)= stanza for single executables (#33)

bin/main.ml

@@ -582,7 +582,8 @@ let exec =
            Format.eprintf "@{<Error>Error@}: Context %S not found!@." context;
            die ""
        in
-       match Context.which context prog with
+       let path = Config.local_install_bin_dir ~context:context.name :: context.path in
+       match Bin.which ~path prog with
        | None ->
          Format.eprintf "@{<Error>Error@}: Program %S not found!@." prog;
          die ""