Found this from graphclasses.org.Two papers give conflicting results for coloring $P_5$-freegraphs  which appear to imply $P=NP$.From Polynomial-time algorithm for vertex k-colorability of P_5-free graphsAbstract. We give the first polynomial-time algorithm for coloring vertices of P5 -free graphs with k colors. This settles an open problem and generalizes several previously known results.From Some new hereditary classes where graph coloring remains NP-hard, p 5... Coloring is NP-hard in $2K_2$-free ... and $\{C_5,P_5\} \cup \ldots$-free$2K_2-free \subset P_5-free$ and the other class contains $P_5$.According to graphclasses, another reason for hardness isclique cover on the complement (another paper), click +Detailsfor references.Question:What is wrong with this seeming contradiction?
Two paper appear to imply collapse via coloring $P_5$-free graphs
cc.complexity theory;graph theory;graph colouring;graph classes
One of those papers is about k-colorability and the other ofthose papers does not specify a constant number of colors.(For a similar example, consider k-variable-SAT versus SAT.)