show precise repos version for dev builds?

Hello,

I use postgres "11devel" packages kindly distributed on
"apt.postgresql.org" and recompiled every few hours.

I wanted to know which version it was, and "11devel" is kind of imprecise.

Ok, there is a hint in the deb package name:

11~~devel~20170930.2214-1~87.git2632bcc.pgdg16.04+1

But this information does not seem to be available from the executables
themselves:

sh> psql --version
psql (PostgreSQL) 11devel

sh> pgbench --version
pgbench (PostgreSQL) 9.6.5

Some projects provide a repository or build date information:

sh> clang --version
clang version 6.0.0 (trunk 314585)

sh> gcc --version
gcc (GCC) 8.0.0 20170930 (experimental)

With some svn project I use "svnversion" which shows a summary of the
status, eg "5432M" which tells that the sources are locally modified
from version 5432.

I would find it useful to have something like that in pg as well, and I
have not found it available.

ISTM that extending the version name with the commit id and or date in
some version output, eg "11devel [2632bcc 2017-09-30 ...]", would do it.

Thoughts?

--
Fabien.