Another unannounced build of Android has been spotted at the Chromium tracker, this one coming courtesy of the eagle-eyed guys at Myce.com. Based on the sparse details in the bug listing, the software appears to be running on both the Nexus 4 and the Nexus 10.
The build number KRS74B likely means that it is Kitkat / Key Lime Pie (K’) builds from the second quarter of this year (‘R’) and the final number is x-th day in the quarter, in this case 74. The final character remarks the build of the day, the B is the second build of that day. What the ‘S’ means is so far unclear.
Android faithful are watching the 4.4 KitKat very closely lately as the next Nexus and platform builds are rumored to debut in the coming month. As of today it appears that mid-October is the expected arrival date for both.