title: dplyr 0.7.5 change in select() behavior
body: <p>select() in dplyr 0.7.5 returns a different result from dplyr 0.7.4 when using a named vector to specify columns. </p>
  
  <pre><code>library(dplyr)                               
  df &lt;- data.frame(a = 1:5, b = 6:10, c = 11:15)
  print(df)                                     
  #&gt;   a  b  c
  #&gt; 1 1  6 11
  #&gt; 2 2  7 12
  #&gt; 3 3  8 13
  #&gt; 4 4  9 14
  #&gt; 5 5 10 15
  
  # a named vector
  cols &lt;- c(x = 'a', y = 'b', z = 'c')          
  print(cols)                                   
  #&gt;  x   y   z 
  #&gt; "a" "b" "c"
  
  # with dplyr 0.7.4
  # returns column names with vector values
  select(df, cols)                              
  #&gt;   a  b  c
  #&gt; 1 1  6 11
  #&gt; 2 2  7 12
  #&gt; 3 3  8 13
  #&gt; 4 4  9 14
  #&gt; 5 5 10 15
  
  # with dplyr 0.7.5
  # returns column names with vector names
  select(df, cols)                              
  #&gt;   x  y  z
  #&gt; 1 1  6 11
  #&gt; 2 2  7 12
  #&gt; 3 3  8 13
  #&gt; 4 4  9 14
  #&gt; 5 5 10 15
  </code></pre>
  
  <p>Is this a bug or a feature?</p>