subminor revision does not fail with svn exported directories

AMDiS/cmake/SetSubMinorRevision.cmake

 #this files sets the cmake variable AMDIS_SUB_MINOR to the subversion global revision
 #if the global revision could not be determined, the variable remains empty
 #TODO: git compatibility
+
+
+macro(Subversion_CHECK_WC dir prefix)
+  set(_Subversion_SAVED_LC_ALL "$ENV{LC_ALL}")
+  set(ENV{LC_ALL} C)
+  execute_process(COMMAND ${Subversion_SVN_EXECUTABLE} info ${dir}
+      OUTPUT_VARIABLE ${prefix}_WC_INFO
+      ERROR_VARIABLE Subversion_svn_info_error
+      RESULT_VARIABLE Subversion_svn_info_result
+      OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+ if(${Subversion_svn_info_result} EQUAL 0)
+   set(${prefix} TRUE)
+   #message(SEND_ERROR "Command \"${Subversion_SVN_EXECUTABLE} info ${dir}\" failed with output:\n${Subversion_svn_info_error}")
+ else()
+   set(${prefix} FALSE)
+ endif()
+  # restore the previous LC_ALL
+    set(ENV{LC_ALL} ${_Subversion_SAVED_LC_ALL})
+  endmacro()
 find_package(Subversion)
 if(Subversion_FOUND)
-   Subversion_WC_INFO(${CMAKE_CURRENT_SOURCE_DIR} svn_info)
-   #message("svn-rev: ${svn_info_WC_REVISION}")
-   set(AMDIS_SUB_MINOR "${svn_info_WC_REVISION}")
+#CMake Version 3.5.2: fatal error in Subversion_WC_INFO if CMAKE_CURRENT_SOURCE_DIR is not a working directory
+   Subversion_CHECK_WC(${CMAKE_CURRENT_SOURCE_DIR} svn_check)
+   if(svn_check)
+     Subversion_WC_INFO(${CMAKE_CURRENT_SOURCE_DIR} svn_info)
+     #message("svn-rev: ${svn_info_WC_REVISION}")
+     set(AMDIS_SUB_MINOR "${svn_info_WC_REVISION}")
+   endif()
  endif()