I've ran both "git clean -xfd" in the checkout dir and "jhbuild buildone -afc" but I still get this issue when jhbuild'ing gcr git master on a Fedora 16 machine:

libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -I.. -I.. -pthread -I/home/andre/opt-gnome/include/glib-2.0 -I/home/andre/opt-gnome//lib/glib-2.0/include -I/home/andre/opt-gnome/include -I/home/andre/opt-gnome/include/p11-kit-1 -DG_LOG_DOMAIN=\"Gcr\" -DGCK_API_SUBJECT_TO_CHANGE -DGCR_API_SUBJECT_TO_CHANGE -DP11_KIT_API_SUBJECT_TO_CHANGE -DGCR_COMPILATION -Wall -Wchar-subscripts -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wpointer-arith -Wcast-align -Wsign-compare -g -O0 -march=prescott -g -Wno-strict-aliasing -Wno-sign-compare -MT libgcr_base_3_la-gcr-key-mechanisms.lo -MD -MP -MF .deps/libgcr_base_3_la-gcr-key-mechanisms.Tpo -c gcr-key-mechanisms.c  -fPIC -DPIC -o .libs/libgcr_base_3_la-gcr-key-mechanisms.o
gcr-key-mechanisms.c:85:1: error: conflicting types for '_gcr_key_mechanisms_check'
gcr-key-mechanisms.h:35:8: note: previous declaration of '_gcr_key_mechanisms_check' was here
gcr-key-mechanisms.c:155:1: error: conflicting types for '_gcr_key_mechanisms_check_async'
gcr-key-mechanisms.h:42:6: note: previous declaration of '_gcr_key_mechanisms_check_async' was here
make[4]: *** [libgcr_base_3_la-gcr-key-mechanisms.lo] Error 1
make[4]: Leaving directory `/home/andre/git-gnome/gcr/gcr'
make[3]: *** [all-recursive] Error 1
make[3]: Leaving directory `/home/andre/git-gnome/gcr/gcr'
make[2]: *** [all] Error 2
make[2]: Leaving directory `/home/andre/git-gnome/gcr/gcr'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/andre/git-gnome/gcr'
make: *** [all] Error 2
*** Error during phase build of gcr: ########## Error running make   *** [1/1]

These files were introduced by a recent commit: http://git.gnome.org/browse/gcr/commit/gcr/?id=df77f1b4561671791b535a89d3f39c7ded35b1e1