_post_form.html.erb

<%= bootstrap_form_for(@post) do |f| %>
  <%= f.text_field  :title, 
                    maxlength: 100, 
                    placeholder: 'Title', 
                    class: 'form-control',
                    required: true, 
                    minlength: 5,
                    maxlength: 100 %>
  <%= f.hidden_field :branch, :value => @branch %>
  <%= f.text_area :content, 
                  rows: 6,
                  required: true, 
                  minlength: 20,
                  maxlength: 1000,
                  placeholder: 'Describe what you are looking for. E.g. specific interests, expertise level, etc.', 
                  class: 'form-control' %>
  <%= f.collection_select :category_id, @categories, :id, :name, class: 'form-control' %>
  <%= f.submit "Create a post", class: 'form-control' %>
<% end %>

maxlength: 100, is repeated twice