Show hash from latest pushed commit in buildinfo

Before this hash of latest local commit was used,
which is not so much useful since nobody can access
that commit hash.

build_files/cmake/buildinfo.cmake

@@ -12,7 +12,7 @@ if(EXISTS ${SOURCE_DIR}/.git/)
 	# The FindSubversion.cmake module is part of the standard distribution
 	include(FindGit)
 	if(GIT_FOUND)
-		execute_process(COMMAND git rev-parse --short HEAD
+		execute_process(COMMAND git rev-parse --short @{u}
 		                WORKING_DIRECTORY ${SOURCE_DIR}
 		                OUTPUT_VARIABLE MY_WC_HASH
 		                OUTPUT_STRIP_TRAILING_WHITESPACE)

build_files/scons/tools/Blender.py

@@ -419,7 +419,7 @@ def buildinfo(lenv, build_type):
             build_commit_timestamp = '0'
             build_branch = 'unknown'
         else:
-            build_hash = os.popen('git rev-parse --short HEAD').read().strip()
+            build_hash = os.popen('git rev-parse --short @{u}').read().strip()
             build_branch = os.popen('git rev-parse --abbrev-ref HEAD').read().strip()
 
             # ## Check for local modifications