ST_ConcaveHull 2.1 regres failure compared to 2.0.3

[robe]

This worked in 2.0.3

SELECT ST_ConcaveHull('SRID=4326;MULTIPOINTM(-71.0821 42.3036 1,-71.0821 67.3036 1,-56.0821 42.3036 1,-56.0821 67.3036 1,-41.0821 42.3036 1,-41.0821 67.3036 1,-26.0821 42.3036 1,-26.0821 67.3036 1,-11.0821 42.3036 1,-11.0821 67.3036 1,3.9179 42.3036 1,3.9179 67.3036 1,18.9179 42.3036 1,18.9179 67.3036 1,33.9179 42.3036 1,33.9179 67.3036 1,48.9179 42.3036 1,48.9179 67.3036 1,-71.0821 42.3036 2,-71.0821 67.3036 2,-56.0821 42.3036 2,-56.0821 67.3036 2,-41.0821 42.3036 2,-41.0821 67.3036 2,-26.0821 42.3036 2,-26.0821 67.3036 2,-11.0821 42.3036 2,-11.0821 67.3036 2,3.9179 42.3036 2,3.9179 67.3036 2,18.9179 42.3036 2,18.9179 67.3036 2,33.9179 42.3036 2,33.9179 67.3036 2,48.9179 42.3036 2,48.9179 67.3036 2)'::geometry
, 0.5,false)

and gave answer:

{{{ — The ST_AsEWKT output — PostgreSQL 9.2.4, compiled by Visual C++ build 1600, 32-bit POSTGIS="2.0.3 r11132" GEOS="3.5.0dev-CAPI-1.9.0 r0" PROJ="Rel. 4.8.0, 6 March 2012" GDAL="GDAL 1.10.0, released 2013/04/24" LIBXML="2.7.8" LIBJSON="UNKNOWN" RASTER

SRID=4326;POLYGON((-71.0821 42.3036,-71.0821 67.3036,48.9179 67.3036,48.9179 42.3036,-71.0821 42.3036)) }}}

Which makes sense if we drop the M as I would expect it to.

In 2.1.0 branch

-- PostgreSQL 9.2.4, compiled by Visual C++ build 1600, 32-bit POSTGIS="2.1.0rc3 r11766" GEOS="3.5.0dev-CAPI-1.9.0 r0" PROJ="Rel. 4.8.0, 6 March 2012" GDAL="GDAL 1.10.0, released 2013/04/24" LIBXML="2.7.8" LIBJSON="UNKNOWN" RASTER


ERROR:  Operation on mixed SRID geometries
CONTEXT:  PL/pgSQL function st_concavehull(geometry,double precision,boolean) line 63 at assignment
********** Error **********

This could be a bug in my code I suppose that it might be missing resetting the SRID but why it worked in 2.0.3 and not in 2.1.0 is a bit troubling.