Change <UNKNOWN> to -UNKNOWN- so exporters can be happy too, when a build was created without svnversion (or from export).

build_files/scons/tools/Blender.py

@@ -282,7 +282,7 @@ def buildinfo(lenv, build_type):
     build_time = time.strftime ("%H:%M:%S")
     build_rev = os.popen('svnversion').read()[:-1] # remove \n
     if build_rev == '': 
-        build_rev = '<UNKNOWN>'
+        build_rev = '-UNKNOWN-'
     if lenv['BF_DEBUG']:
         build_type = "Debug"
     else: