Trying to green the tree. Why are we seeing these different variations?

chrome/test/data/reliability/known_crashes.txt

Index: chrome/test/data/reliability/known_crashes.txt
===================================================================
--- chrome/test/data/reliability/known_crashes.txt	(revision 16287)
+++ chrome/test/data/reliability/known_crashes.txt	(working copy)
@@ -104,7 +104,6 @@
 PREFIX : tcmalloc::threadcache::fetchfromcentralcache___tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___`anonymous namespace'::cpp_alloc___operator new[]___std::_allocate<userscript>___std::vector<gurl,std::allocator<gurl> >::_insert_n___std::vector<gurl,std::allocator<gurl> >::insert___std::vector<gurl,std::allocator<gurl> >::push_back___webframeloaderclient::dispatchdidreceiveserverredirectforprovisionalload___webcore::documentloader::setrequest
 PREFIX : tcmalloc::threadcache::fetchfromcentralcache___tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___`anonymous namespace'::cpp_alloc___operator new___std::_allocate<gurl>___std::vector<gurl,std::allocator<gurl> >::_insert_n___std::vector<gurl,std::allocator<gurl> >::insert___std::vector<gurl,std::allocator<gurl> >::push_back___webframeloaderclient::dispatchdidreceiveserverredirectforprovisionalload___webcore::documentloader::setrequest
 PREFIX : tcmalloc::threadcache::fetchfromcentralcache___tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___`anonymous namespace'::cpp_alloc___operator new[]___std::_allocate<gurl>___std::vector<gurl,std::allocator<gurl> >::_insert_n___std::vector<gurl,std::allocator<gurl> >::insert___std::vector<gurl,std::allocator<gurl> >::push_back___webframeloaderclient::dispatchdidreceiveserverredirectforprovisionalload___webcore::documentloader::setrequest
-PREFIX : tcmalloc::threadcache::fetchfromcentralcache___tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___`anonymous namespace'::cpp_alloc___operator new[]___std::_allocate<short>___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::_copy___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::append___std::operator+<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >___safebrowsingdatabasebloom::init
 
 
 # 10901?  This stack looks odd
@@ -113,5 +112,7 @@
 # 8875
 PREFIX : _87except____startoneargerrorhandling___sqrt___v8::internal::invoke___v8::internal::execution::call
 
-# 12154
-PREFIX : tcmalloc::threadcache::fetchfromcentralcache___tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___`anonymous namespace'::cpp_alloc___operator new[]___std::_allocate<unsigned short>___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::_copy___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::append___std::operator+<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >___safebrowsingdatabasebloom::init___safebrowsingservice::getdatabase
+# 12154; what's with these variations?
+PREFIX : tcmalloc::threadcache::fetchfromcentralcache___tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___`anonymous namespace'::cpp_alloc___operator new[]___std::_allocate<unsigned short>___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::_copy___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::append___std::operator+<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >___safebrowsingdatabasebloom::init
+PREFIX : tcmalloc::threadcache::fetchfromcentralcache___tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___`anonymous namespace'::cpp_alloc___operator new[]___std::_allocate<short>___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::_copy___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::append___std::operator+<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >___safebrowsingdatabasebloom::init
+PREFIX : tcmalloc::threadcache::fetchfromcentralcache___tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___`anonymous namespace'::cpp_alloc___operator new[]___std::_allocate<wchar_t>___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::_copy___std::basic_string<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >::append___std::operator+<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t> >___safebrowsingdatabasebloom::init