A new PROJ4 version came out on 10-Sep-2015 (https://github.com/OSGeo/proj.4/wiki) which ships an important bugfix (in the 4.9.1 release the file "proj_def.dat" was left out by accident):

Related ChangeLog snippet:

2015-09-06 Even Rouault <even rouault spatialys.com>
	* re-add proj_def.dat which was missing from source distribution
	https://github.com/OSGeo/proj.4/issues/274
	https://github.com/OSGeo/proj.4/issues/296 and
	https://github.com/OSGeo/proj.4/issues/297

The package is available here:
https://download.osgeo.org/proj/proj-4.9.2.tar.gz

Please updates the package for this important fix.
Thanks.

--------------------------------------------------
Full proj-4.9.2 ChangeLog:

2015-09-10 sisyphus <https://github.com/sisyphus>
	* : Rename PVALUE in pj_param.cto prevent Windows variable name clash

2015-09-10 Bas Couwenberg <https://github.com/sebastic>
	* : Don't include files in proj dist, also included in proj-datumgrids
	dist #301

2015-09-10 Ture Pålsson <https://github.com/turepalsson>
	* : PTHREAD_MUTEX_RECURSIVE detection issue on FreeBSD #303

2015-09-10 Martin Raspaud <https://github.com/mraspaud>
	* : Don't return values when doing inverse projections outside of the
	mollweide map #304

2015-09-08 Charles Karney <https://github.com/cffk>
	* : Update Geodesic library from GeographicLib
		* Improve accuracy of calculations by evaluating trigonometric
		  functions more carefully and replacing the series for the reduced
		  length with one with a smaller truncation error.
		* The allowed ranges for longitudes and azimuths is now unlimited; it
		  used to be [-540d, 540d).
		* Enforce the restriction of latitude to [-90d, 90d] by returning NaNs
		  if the latitude is outside this range.
		* The inverse calculation sets s12 to zero for coincident points at
		  pole (instead of returning a tiny quantity).
		* This commit also includes a work-around for an inaccurate value for
		  pi/180 in dmstor.c (see the definitions of DEG_IN and DEG_OUT in
		  geod_interface.c).

2015-09-06 Even Rouault <even.rouault>
	* re-add proj_def.dat which was missing from source distribution
	https://github.com/OSGeo/proj.4/issues/274
	https://github.com/OSGeo/proj.4/issues/296 and
	https://github.com/OSGeo/proj.4/issues/297

2015-07-27 Even Rouault <even.rouault>
	* : Remove setlocale() use in pj_init_ctx(), and replace uses of atof() &
	strtod() by their locale safe variants pj_atof() and pj_strtod().
	Proj versions from now advertize #define PJ_LOCALE_SAFE 1 in proj_api.h
	and export pj_atof() & pj_strtod() (#226)

2015-06-01 Charles Karney <https://github.com/cffk>
	Make PJ_aeqd.c use geodesics for inverse and forward projection
	modification so that the geodesic structure is not global
	https://github.com/OSGeo/proj.4/pull/281

2015-05-25 Elliott Sales de Andrade <https://github.com/QuLogic>
	* : Fix inverse stereo projection on an ellipsoid
	https://github.com/OSGeo/proj.4/pull/277