sdk: fix generation of base feed url

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

target/sdk/Makefile

@@ -37,7 +37,7 @@ SDK_DIRS = \
 BASE_FEED:=$(shell git config --get remote.origin.url 2>/dev/null | sed -ne 's/^/src-git base /p')
 BASE_FEED:=$(if $(BASE_FEED),$(BASE_FEED),$(shell cd $(TOPDIR); LC_ALL=C git svn info 2>/dev/null | sed -ne 's/^URL: /src-gitsvn base /p'))
 BASE_FEED:=$(if $(BASE_FEED),$(BASE_FEED),$(shell cd $(TOPDIR); LC_ALL=C svn info 2>/dev/null | sed -ne 's/^URL: /src-svn base /p'))
-BASE_FEED:=$(if $(BASE_FEED),$(BASE_FEED),src-git base https://git.openwrt.org/$(filter-out unknown/ r%/,$(subst $(space),.,$(wordlist 1,2,$(subst .,$(space),$(VERSION_NUMBER))))/)openwrt.git)
+BASE_FEED:=$(if $(BASE_FEED),$(BASE_FEED),src-git base https://git.lede-project.org/source.git$(filter-out ;master,;$(shell git rev-parse --abbrev-ref HEAD)))
 
 KDIR_BASE = $(patsubst $(TOPDIR)/%,%,$(LINUX_DIR))