Looks like the IS-GPS-200 documents 2 frequencies called L1 and L2. L2 fixes this but is a different frequency : http://www.catb.org/gpsd/hacking.html#y2k1 and https://www.gps.gov/technical/icwg/IS-GPS-200H.pdf (for "frequency")
"1575.42 MHz (10.23 MHz × 154) called L1;
and a second at 1227.60 MHz (10.23 MHz × 120), called L2."
CNAV is wrapped up in L2 but L2 is "pre-operational" and not to be used for critical usage.
L1 C/A (under "Legacy Signals" in Wiki has a section about 10 bits and rollover) is affected. L2C CNAV ("pre-operational") is not (blurb in wiki under "CNAV navigation message" explains increase in bits).
https://en.wikipedia.org/wiki/GPS_signals was also helpful.
Sounds like some newer receivers are on the L2 bandwagon.. but that doesn't mean there isn't a tonne of L1 only devices still around.