Tstory goes, when the CP/M User Group distributed disk #5 in 1977 it included some original source code from Gary Kildall 1975. Original PL/M source for CP/M including FDOS, BDOS and PIP .

Apparently they were told to stop that and subsequent disks had it deleted from the directory but pieces of it remained on the disk. The CPMUG5 disk I have apparently was one of these.