a bug of a predicate push down in hive

gistfile1.sql

create table src_tbl (
    key string,
    value string
);

create table tbl_a (
    key string,
    value string
);

create table tbl_b (
    key string,
    value string
);

EXPLAIN FROM (
    FROM src_tbl
    SELECT TRANSFORM(key, value)
    USING 'cat'
) t
INSERT OVERWRITE TABLE tbl_a SELECT key, value WHERE key = 'a'
INSERT OVERWRITE TABLE tbl_b SELECT key, value WHERE key = 'b';

gistfile2.txt

hive> EXPLAIN FROM (
    >     FROM src_tbl
    >     SELECT TRANSFORM(key, value)
    >     USING 'cat'
    > ) t
    > INSERT OVERWRITE TABLE tbl_a SELECT key, value WHERE key = 'a'
    > INSERT OVERWRITE TABLE tbl_b SELECT key, value WHERE key = 'b';
OK
ABSTRACT SYNTAX TREE:
  (TOK_QUERY (TOK_FROM (TOK_SUBQUERY (TOK_QUERY (TOK_FROM (TOK_TABREF (TOK_TABNAME src_tbl))) (TOK_INSERT (TOK_DESTINATION (TOK_DIR TOK_TMP_FILE)) (TOK_SELECT (TOK_SELEXPR (TOK_TRANSFORM (TOK_EXPLIST (TOK
_TABLE_OR_COL key) (TOK_TABLE_OR_COL value)) TOK_SERDE TOK_RECORDWRITER 'cat' TOK_SERDE TOK_RECORDREADER))))) t)) (TOK_INSERT (TOK_DESTINATION (TOK_TAB (TOK_TABNAME tbl_a))) (TOK_SELECT (TOK_SELEXPR (TOK_
TABLE_OR_COL key)) (TOK_SELEXPR (TOK_TABLE_OR_COL value))) (TOK_WHERE (= (TOK_TABLE_OR_COL key) 'a'))) (TOK_INSERT (TOK_DESTINATION (TOK_TAB (TOK_TABNAME tbl_b))) (TOK_SELECT (TOK_SELEXPR (TOK_TABLE_OR_CO
L key)) (TOK_SELEXPR (TOK_TABLE_OR_COL value))) (TOK_WHERE (= (TOK_TABLE_OR_COL key) 'b'))))

STAGE DEPENDENCIES:
  Stage-2 is a root stage
  Stage-8 depends on stages: Stage-2 , consists of Stage-5, Stage-4, Stage-6
  Stage-5
  Stage-0 depends on stages: Stage-5, Stage-4, Stage-7
  Stage-3 depends on stages: Stage-0
  Stage-4
  Stage-6
  Stage-7 depends on stages: Stage-6
  Stage-14 depends on stages: Stage-2 , consists of Stage-11, Stage-10, Stage-12
  Stage-11
  Stage-1 depends on stages: Stage-11, Stage-10, Stage-13
  Stage-9 depends on stages: Stage-1
  Stage-10
  Stage-12
  Stage-13 depends on stages: Stage-12

STAGE PLANS:
  Stage: Stage-2
    Map Reduce
      Alias -> Map Operator Tree:
        t:src_tbl
          TableScan
            alias: src_tbl
            Select Operator
              expressions:
                    expr: key
                    type: string
                    expr: value
                    type: string
              outputColumnNames: _col0, _col1
              Transform Operator
                command: cat
                output info:
                    input format: org.apache.hadoop.mapred.TextInputFormat
                    output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
                Filter Operator
                  predicate:
                      expr: ((_col0 = 'a') and (_col0 = 'b'))
... 

expr: ((_col0 = 'a') and (_col0 = 'b')) <- all inserts result in 0 row...