Fix ocaml#32

Now the environment variables can't have more than one ~/.opam/... path

src/client.ml

@@ -701,10 +701,11 @@ type env = {
 let expand_env t env =
   List.map (fun (ident, symbol, string) ->
     let string = substitute_string t string in
+    let clean_env () = try Utils.reset_env_value (Sys.getenv ident) with _ -> [] in
     match symbol with
     | "="  -> (ident, string)
-    | "+=" -> (ident, try string ^ ":" ^ Sys.getenv ident with _ -> string)
-    | "=+" -> (ident, try Sys.getenv ident ^ ":" ^ string with _ -> string)
+    | "+=" -> (ident, String.concat ":" (string :: clean_env ()))
+    | "=+" -> (ident, String.concat ":" (clean_env () @ [string]))
     | _    -> failwith (Printf.sprintf "expand_env: %s is an unknown symbol" symbol)
   ) env
 

src/run.ml

@@ -180,17 +180,17 @@ let real_path p =
   else
     dir / base
 
-let add_path bins = 
+let replace_path bins = 
   let path = ref "<not set>" in
   let env = Unix.environment () in
   for i = 0 to Array.length env - 1 do
     let k,v = match Utils.cut_at env.(i) '=' with
       | Some (k,v) -> k,v
       | None       -> assert false in
     if k = "PATH" then
-    let new_path = match List.filter Sys.file_exists bins with
-      | [] -> v
-      | l  -> String.concat ":" l ^ ":" ^ v in
+    let v = Utils.reset_env_value v in
+    let bins = List.filter Sys.file_exists bins in
+    let new_path = String.concat ":" (bins @ v) in
     env.(i) <- "PATH=" ^ new_path;
     path := new_path;
   done;
@@ -201,7 +201,7 @@ type command = string list
 let run_process ?(add_to_env=[]) ?(add_to_path=[]) = function
   | []           -> invalid_arg "run_process"
   | cmd :: args ->
-      let env, path = add_path add_to_path in
+      let env, path = replace_path add_to_path in
       let add_to_env = List.map (fun (k,v) -> k^"="^v) add_to_env in
       let env = Array.concat [ env; Array.of_list add_to_env ] in
       let name = log_file () in

src/utils.ml

@@ -77,4 +77,10 @@ let cut_at = cut_at_aux String.index
 
 let rcut_at = cut_at_aux String.rindex
 
+let split s c =
+  Pcre.split (Pcre.regexp (String.make 1 c)) s
 
+(* Remove from a ':' separated list of string the one which are prefix of Globals.root_path *)
+let reset_env_value v =
+  let v = split v ':' in
+  List.filter (fun v -> not (starts_with ~prefix:!Globals.root_path v)) v