I would have sworn that I had compiled both 7.1.2 and 7.1.3 with BLCKSZ 16384. The 1262 files is evidence that isn't true and that 7.1.2 was running with BLCKSZ 8192, unless that is, something can truncate a file and not change the modification date.
It's kind of ugly that something in the process wasted the pg_control. My suspicion is that the corruption occurred when I did a "make check". I wouldn't have thought that a "make check" would be harmful to an existing installation, and there is nothing in the documentation that suggests that it is, but I am pretty sure that "make check" does an initdb, and I'm into thinking it was an erroneous initdb that skewered me.