make sure it also works when there are no git tags

gyp/version.gypi

@@ -14,7 +14,7 @@
             '<(SHARED_INTERMEDIATE_DIR)/include/mbgl/util/version.hpp',
             '<(SHARED_INTERMEDIATE_DIR)/src/mbgl/util/mbgl_version.cpp',
           ],
-          'action': ['<@(python)', 'scripts/build-version.py', '<(SHARED_INTERMEDIATE_DIR)', '<!@(git describe --tags --abbrev=0)', '<!@(git rev-parse --short HEAD)'],
+          'action': ['<@(python)', 'scripts/build-version.py', '<(SHARED_INTERMEDIATE_DIR)', '<!@(git describe --tags --always --abbrev=8)', '<!@(git rev-parse --short=8 HEAD)'],
         }
       ],
       'direct_dependent_settings': {

scripts/build-version.py

@@ -4,7 +4,13 @@ import sys, os, errno
 
 
 output_dir = sys.argv[1]
-tag = map(int, sys.argv[2].split('.'))
+
+# When they're identical, the git describe can't find a tag and reports the rev instead.
+if sys.argv[2] == sys.argv[3]:
+    tag = [0, 0, 0]
+else:
+    tag = map(int, sys.argv[2].split('.'))
+
 rev = sys.argv[3]