COMMIT ||= and &&= may not make an assignment at all.	http://github.com/rubyspec/rubyspec/commit/145bb603a5c146634ad085ccb1ab3e957cc72113
COMMIT Separate ||= and &&= from other operators	http://github.com/rubyspec/rubyspec/commit/a2278176e24a596fd85e3f332f5410d7dd3eb5cf

===================================================================
+++ 20100325T075514
@@ 12 @@
 URL: http://svn.ruby-lang.org/repos/ruby/branches/ruby_1_9_1
 リポジトリのルート: http://svn.ruby-lang.org/repos/ruby
 リポジトリ UUID: b2dd03c8-39d4-4d8f-98ff-823fe69b080e
+リビジョン: 27038
 ノード種別: ディレクトリ
 準備中の処理: 特になし
 最終変更者: yugui
@@ 19946 @@
 /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/ruby/ext/socket/extconf.rb:<line_a>: warning: ambiguous first argument; put parentheses or even spaces
 /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/ruby/ext/json/lib/json/editor.rb:<line_a>: warning: shadowing outer local variable - item
 <elapsed> s: .
+TestSystem#test_system: /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/tmp/ruby_script_tmp20100325-16882-14djsbm/ruby_script_tmp.16882:<line_a>: warning: global variable `$zzz' not initialized
 <elapsed> s: .
 TestTCPSocket#test_encoding: <elapsed> s: .
 TestTCPSocket#test_recvfrom: <elapsed> s: .
@@ 57997 @@
 - assigns the lhs if previously unassigned
 - checks for class variable definition before fetching its value
 
+Unconditional operator assignment 'var op= expr'
 - is equivalent to 'var = var op expr'
 
+Conditional operator assignment 'var op= expr'
+- assigns the lhs if its truthiness is false for ||, true for &&
+- may not assign at all, depending on the truthiness of lhs
+- uses short-circuit arg evaluation
 
+Unconditional operator assignment 'obj.meth op= expr'
 - is equivalent to 'obj.meth = obj.meth op expr'
 
+Conditional operator assignment 'obj.meth op= expr'
+- is equivalent to 'obj.meth op obj.meth = expr'
+- may not assign at all, depending on the truthiness of lhs
+- uses short-circuit arg evaluation
 
 Operator assignment 'obj.meth op= expr'
 - evaluates lhs one time
 
+Unconditional operator assignment 'obj[idx] op= expr'
 - is equivalent to 'obj[idx] = obj[idx] op expr'
 
+Conditional operator assignment 'obj[idx] op= expr'
+- is equivalent to 'obj[idx] op obj[idx] = expr'
+- may not assign at all, depending on the truthiness of lhs
+- uses short-circuit arg evaluation
 
 Operator assignment 'obj[idx] op= expr'
 - handles complex index (idx) arguments
@@ 58066 @@
 
 Finished in <t> seconds
 
+1 file, 70 examples, 494 expectations, 0 failures, 0 errors
 == rubyspec/language/while_spec.rb # <time>
 + bin/ruby mspec/bin/mspec -V -f s -B /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/rubyspec/ruby.1.9.mspec -t /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/bin/ruby rubyspec/language/while_spec.rb
 ruby <version>
@@ 71621 @@
 
 Finished in <t> seconds
 
+1 file, 36 examples, 113025 expectations, 0 failures, 0 errors
 == rubyspec/library/prime/instance_spec.rb # <time>
 + bin/ruby mspec/bin/mspec -V -f s -B /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/rubyspec/ruby.1.9.mspec -t /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/bin/ruby rubyspec/library/prime/instance_spec.rb
 ruby <version>

===================================================================
--- 20100324T080023
@@ 12 @@
 URL: http://svn.ruby-lang.org/repos/ruby/branches/ruby_1_9_1
 リポジトリのルート: http://svn.ruby-lang.org/repos/ruby
 リポジトリ UUID: b2dd03c8-39d4-4d8f-98ff-823fe69b080e
-リビジョン: 27027
 ノード種別: ディレクトリ
 準備中の処理: 特になし
 最終変更者: yugui
@@ 19946 @@
 /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/ruby/ext/socket/extconf.rb:<line_a>: warning: ambiguous first argument; put parentheses or even spaces
 /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/ruby/ext/json/lib/json/editor.rb:<line_a>: warning: shadowing outer local variable - item
 <elapsed> s: .
-TestSystem#test_system: /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/tmp/ruby_script_tmp20100324-29091-14djsbm/ruby_script_tmp.29091:<line_a>: warning: global variable `$zzz' not initialized
 <elapsed> s: .
 TestTCPSocket#test_encoding: <elapsed> s: .
 TestTCPSocket#test_recvfrom: <elapsed> s: .
@@ 57997 @@
 - assigns the lhs if previously unassigned
 - checks for class variable definition before fetching its value
 
-Operator assignment 'var op= expr'
 - is equivalent to 'var = var op expr'
-- uses short-circuit arg evaluation for operators ||= and &&=
 
 Operator assignment 'obj.meth op= expr'
 - is equivalent to 'obj.meth = obj.meth op expr'
-- uses short-circuit arg evaluation for operators ||= and &&=
 - evaluates lhs one time
 
 Operator assignment 'obj[idx] op= expr'
 - is equivalent to 'obj[idx] = obj[idx] op expr'
-- uses short-circuit arg evaluation for operators ||= and &&=
 - handles complex index (idx) arguments
 - returns result of rhs not result of []=
 
@@ 58050 @@
 
 Finished in <t> seconds
 
-1 file, 64 examples, 484 expectations, 0 failures, 0 errors
 == rubyspec/language/while_spec.rb # <time>
 + bin/ruby mspec/bin/mspec -V -f s -B /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/rubyspec/ruby.1.9.mspec -t /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/bin/ruby rubyspec/language/while_spec.rb
 ruby <version>
@@ 71605 @@
 
 Finished in <t> seconds
 
-1 file, 36 examples, 95301 expectations, 0 failures, 0 errors
 == rubyspec/library/prime/instance_spec.rb # <time>
 + bin/ruby mspec/bin/mspec -V -f s -B /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/rubyspec/ruby.1.9.mspec -t /home/chkbuild/tmp/build/ruby-1.9.1/<buildtime>/bin/ruby rubyspec/library/prime/instance_spec.rb
 ruby <version>