$REPO_HASH {$gqueried_repo} {REPO_BRANCHES} = @branch_list  ;
  # Does not do what you apparently think it does
  # The result of the assignment above is the number of elements in @branch_list

##</code><code>##

$REPO_HASH {$gqueried_repo} {REPO_BRANCHES} = \@branch_list;
   #Note: Added "\", which makes it a REF to the array

##</code><code>##

  for my $k (@{ $REPO_HASH {$gqueried_repo} {REPO_BRANCHES} }){
     # Process one item of the array in $k
  }