"Git was inspired in part by Larry McVoy's BitKeeper, which was
considered by Linus to be the most advanced SCM available at the
time. Mr. McVoy had the services of the best programmers in the
world using and improving BitKeeper, and they got free use of
BitKeeper, but it was an uneasy alliance. Using BitKeeper for
kernel development was controversial because it is a closed,
proprietary product. Linus and some other key developers liked it,
but Alan Cox, Andrew Tridgell, and other developers didn't like the
idea of using a proprietary VCS for Linux kernel development, and
refused to use it. Mr. McVoy exacerbated the situation by
continually changing the terms of the BitKeeper license and
imposing ever-more stringent restrictions, such as not implementing
any of the BitKeeper ideas or concepts in other products.
"Tridge ignited a major firestorm by writing a Free client for
BitKeeper, which would have allowed kernel developers who did not
want to use the proprietary BitKeeper clients to have equal access.
Shortly after that Mr. McVoy revoked all of the "free use" licenses
and required anyone who wanted to continue to use BitKeeper to
switch to the commercial version. In addition he refused to allow
any OSDL (Open Source Development Lab) employees, which included
Linus Torvalds, to use BitKeeper at all."