Fix: Exporting from a SQLFORM.grid with customized search queries

Massimo manually applied older diff file.
He also merged my newer diff file. So Optimized code

gluon/sqlhtml.py

@@ -2326,7 +2326,7 @@ class SQLFORM(FORM):
                              expcolumns.append(str(field))
 
             if export_type in exportManager and exportManager[export_type]:
-                if keywords and not callable(searchable):
+                if keywords:
                     try:
                         #the query should be constructed using searchable
                         #fields but not virtual fields
@@ -2343,19 +2343,6 @@ class SQLFORM(FORM):
                     except Exception, e:
                         response.flash = T('Internal Error')
                         rows = []
-                elif callable(searchable):
-                    #use custom_query using searchable
-                    try:
-                        #the query should be constructed using searchable
-                        #fields but not virtual fields
-                        sfields = reduce(lambda a, b: a + b,
-                            [[f for f in t if f.readable and not isinstance(f, Field.Virtual)] for t in tables])
-                        dbset = dbset(searchable(sfields, keywords))
-                        rows = dbset.select(left=left, orderby=orderby,
-                                            cacheable=True, *selectable_columns)
-                    except Exception, e:
-                        response.flash = T('Internal Error')
-                        rows = []
                 else:
                     rows = dbset.select(left=left, orderby=orderby,
                                         cacheable=True, *selectable_columns)