With just installed pg_shere from current master, and we observe difference in reported version numbers between pg_sphere_version() and extension version:

=> select pg_sphere_version();
 pg_sphere_version
-------------------
 1.1.5

=> SELECT extversion from pg_catalog.pg_extension where extname = 'pg_sphere';
 extversion
------------
 1.2.0

Aren't they supposed to be the same?