Revert "Throw a specific error for incomplete parse errors."

This reverts commit 6498adb002. We don't
actually use IncompleteParseError in 'nix repl'.

src/libexpr/lexer.l

@@ -213,7 +213,5 @@ or          { return OR_KW; }
 
 }
 
-<<EOF>> { data->atEnd = true; return 0; }
-
 %%
 

src/libexpr/nixexpr.hh

@@ -11,7 +11,6 @@ namespace nix {
 
 MakeError(EvalError, Error)
 MakeError(ParseError, Error)
-MakeError(IncompleteParseError, ParseError)
 MakeError(AssertionError, EvalError)
 MakeError(ThrownError, AssertionError)
 MakeError(Abort, EvalError)

src/libexpr/parser.y

@@ -31,12 +31,10 @@ namespace nix {
         Path basePath;
         Symbol path;
         string error;
-        bool atEnd;
         Symbol sLetBody;
         ParseData(EvalState & state)
             : state(state)
             , symbols(state.symbols)
-            , atEnd(false)
             , sLetBody(symbols.create("<let-body>"))
             { };
     };
@@ -541,12 +539,7 @@ Expr * EvalState::parse(const char * text,
     int res = yyparse(scanner, &data);
     yylex_destroy(scanner);
 
-    if (res) {
-      if (data.atEnd)
-        throw IncompleteParseError(data.error);
-      else
-        throw ParseError(data.error);
-    }
+    if (res) throw ParseError(data.error);
 
     data.result->bindVars(staticEnv);