Re: [PATCH 1/2] trace2: rename environment variables to GIT_TRACE2*

> For an environment variable that is supposed to be set by users, the
> GIT_TR2* env vars are just too unclear, inconsistent, and ugly.
>
> Most of the established GIT_* environment variables don't use
> abbreviations, and in case of the few that do (GIT_DIR,
> GIT_COMMON_DIR, GIT_DIFF_OPTS) it's quite obvious what the
> abbreviations (DIR and OPTS) stand for.  But what does TR stand for?
> Track, traditional, trailer, transaction, transfer, transformation,
> transition, translation, transplant, transport, traversal, tree,
> trigger, truncate, trust, or ...?!
>
> The trace2 facility, as the '2' suffix in its name suggests, is
> supposed to eventually supercede Git's original trace facility.  It's
> reasonable to expect that the corresponding environment variables
> follow suit, and after the original GIT_TRACE variables they are
> called GIT_TRACE2; there is no such thing is 'GIT_TR'.
>
> All trace2-specific config variables are, very sensibly, in the
> 'trace2' section, not in 'tr2'.
>
> OTOH, we don't gain anything at all by omitting the last three
> characters of "trace" from the names of these environment variables.
>
> So let's rename all GIT_TR2* environment variables to GIT_TRACE2*,
> before they make their way into a stable release.