Of course I messed up generating the version header.

Trailing zeros, undef'd "falsy" variable. Sigh.

src/Magnum/CMakeLists.txt

@@ -38,10 +38,12 @@ if(Git_FOUND)
         OUTPUT_VARIABLE MAGNUM_VERSION_STRING
         RESULT_VARIABLE _MAGNUM_VERSION_RESULT
         ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
-    if(MAGNUM_VERSION_STRING MATCHES "^v([0-9][0-9][0-9][0-9])\\.0?([0-9][0-9])-([0-9]+)-g([a-f0-9]+)$")
+    if(MAGNUM_VERSION_STRING MATCHES "^v([0-9][0-9][0-9][0-9])\\.0?([0-9][0-9]?)-([0-9]+)-g([a-f0-9]+)$")
         set(MAGNUM_VERSION_YEAR ${CMAKE_MATCH_1})
         set(MAGNUM_VERSION_MONTH ${CMAKE_MATCH_2})
         set(MAGNUM_VERSION_COMMIT ${CMAKE_MATCH_3})
+        # Otherwise if commit is 0, it would #undef the variable
+        set(MAGNUM_VERSION_COMMIT " ${MAGNUM_VERSION_COMMIT}")
         set(MAGNUM_VERSION_HASH ${CMAKE_MATCH_4})
     elseif(_MAGNUM_VERSION_RESULT EQUAL 0)
         message(WARNING "Can't match Git version from ${MAGNUM_VERSION_STRING}")

src/Magnum/version.h.cmake

@@ -31,7 +31,7 @@
 
 #define MAGNUM_VERSION_YEAR ${MAGNUM_VERSION_YEAR}
 #define MAGNUM_VERSION_MONTH ${MAGNUM_VERSION_MONTH}
-#cmakedefine MAGNUM_VERSION_COMMIT ${MAGNUM_VERSION_COMMIT}
+#cmakedefine MAGNUM_VERSION_COMMIT${MAGNUM_VERSION_COMMIT}
 #cmakedefine MAGNUM_VERSION_HASH 0x${MAGNUM_VERSION_HASH}
 #cmakedefine MAGNUM_VERSION_STRING "${MAGNUM_VERSION_STRING}"