As the observer starts moving in the same direction as the light waves, the velocity of the waves relative to him decreases, in violation of special relativity:
http://www.phys.uconn.edu/~gibson/Notes/Section6_3/Sec6_3.htm Professor George N. Gibson, University of Connecticut: "However, if either the source or the observer is moving, things change. This is called the Doppler effect. (...) To understand the moving observer, imagine you are in a motorboat on the ocean. If you are not moving, the boat will bob up and down with a certain frequency determined by the ocean waves coming in. However, imagine that you are moving into the waves fairly quickly. You will find that you bob up and down more rapidly, because you hit the crests of the waves sooner than if you were not moving. So, the frequency of the waves appears to be higher to you than if you were not moving. Notice, THE WAVES THEMSELVES HAVE NOT CHANGED, only your experience of them. Nevertheless, you would say that the frequency has increased. Now imagine that you are returning to shore, and so you are traveling in the same direction as the waves. In this case, the waves may still overtake you, but AT A MUCH SLOWER RATE - you will bob up and down more slowly. In fact, if you travel with exactly the same speed as the waves, you will not bob up and down at all. The same thing is true for sound waves, or ANY OTHER WAVES."
That the velocity of the light waves (relative to the observer) decreases is clearly seen in this video (although Eusebi obeys Ignatius of Loyola's principle and says the velocity remains the same):
Ignatius of Loyola: "That we may be altogether of the same mind and in conformity with the Church herself, if she shall have defined anything to be black which appears to our eyes to be white, we ought in like manner to pronounce it to be black."