How come 'Value2' is changed to 'Value_two', but 'key2' is unchanged?

qwurx [shmem] 15:35 ~ > perl -MDevel::Peek -e '%hash = qw(a 1 b 2 c 3)
+; for(%hash){print STDERR "$_: ";Dump $_; s/b/d/;} print "$_ => $hash
+{$_}\n" for sort keys %hash'
c: SV = PVIV(0x8168b10) at 0x8166b44
  REFCNT = 2
  FLAGS = (POK,FAKE,READONLY,pPOK)
  IV = -289776295
  PV = 0x8187928 "c"
  CUR = 1
  LEN = 0
3: SV = PV(0x8167ae8) at 0x8167894
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x818f380 "3"\0
  CUR = 1
  LEN = 4
a: SV = PVIV(0x8168b20) at 0x8166cf4
  REFCNT = 2
  FLAGS = (POK,FAKE,READONLY,pPOK)
  IV = -902917054
  PV = 0x817be80 "a"
  CUR = 1
  LEN = 0
1: SV = PV(0x8167b00) at 0x8166c28
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x817ecb0 "1"\0
  CUR = 1
  LEN = 4
b: SV = PVIV(0x8168b50) at 0x818dfd8
  REFCNT = 2
  FLAGS = (POK,FAKE,READONLY,pPOK)
  IV = 14385563
  PV = 0x81876b0 "b"
  CUR = 1
  LEN = 0
2: SV = PV(0x8167ba8) at 0x8166d90
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x81866b0 "2"\0
  CUR = 1
  LEN = 4
a => 1
b => 2
c => 3
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The flags for a hash key are (POK,FAKE,READONLY,pPOK), for values they are (POK,pPOK). Which means you manipulate the actual content modifying a value, but you're operating on fake variables modifying the keys.

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