Did you run the code the OP posted? Since at least 5.6.1, the $1 set by the regexp inside the if is no longer in scope outside the if. The following illustrates this clearly.

'a' =~ /(.)/;

{
   'b' =~ /(.)/;
   print("$1\n");  # b
}

print("$1\n");     # a
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This is documented in perlvar.