Revert "Update revision.h if branch unmatch not only revision"

This reverts commit 5a332940ed.
Something does not work well on Github Actions.

defs/gmake.mk

@@ -429,19 +429,14 @@ endif
 
 ifeq ($(HAVE_GIT),yes)
 REVISION_LATEST := $(shell $(CHDIR) $(srcdir) && $(GIT) log -1 --format=%H 2>/dev/null)
-BRANCH_LATEST := $(shell $(CHDIR) $(srcdir) && $(GIT) symbolic-ref --short HEAD 2>/dev/null)
 else
 REVISION_LATEST := update
-BRANCH_LATEST :=
 endif
-revision.h := $(wildcard $(srcdir)/revision.h revision.h)
-REVISION_IN_HEADER := $(if $(revision.h),\
-	$(shell sed '/^\#define RUBY_FULL_REVISION "\(.*\)"/!d;s//\1/;q' $(revision.h)))
-BRANCH_IN_HEADER := $(if $(revision.h),\
-	$(shell sed '/^\#define RUBY_BRANCH_NAME \(".*"\)/!d;s//\1/;s,.* // ,,;s/"//g;q' $(revision.h)))
-REVISION_IN_HEADER := $(if $(REVISION_IN_HEADER),$(REVISION_IN_HEADER),none)
-BRANCH_IN_HEADER := $(if $(BRANCH_IN_HEADER),$(BRANCH_IN_HEADER),...)
-ifneq ($(REVISION_IN_HEADER):$(BRANCH_IN_HEADER),$(REVISION_LATEST):$(BRANCH_LATEST))
+REVISION_IN_HEADER := $(shell sed '/^\#define RUBY_FULL_REVISION "\(.*\)"/!d;s//\1/;q' $(wildcard $(srcdir)/revision.h revision.h) /dev/null 2>/dev/null)
+ifeq ($(REVISION_IN_HEADER),)
+REVISION_IN_HEADER := none
+endif
+ifneq ($(REVISION_IN_HEADER),$(REVISION_LATEST))
 $(REVISION_H): PHONY
 endif
 

tool/lib/vcs.rb

@@ -256,9 +256,8 @@ class VCS
     if branch
       e = '..'
       name = branch.sub(/\A(.{#{limit-e.size}}).{#{e.size+1},}/o) {$1+e}
-      (name = name.dump).gsub!(/\\#/, '#')
-      comment = " // #{branch}" unless name == %["#{branch}"]
-      code << "#define RUBY_BRANCH_NAME #{name}#{comment}"
+      name = name.dump.sub(/\\#/, '#')
+      code << "#define RUBY_BRANCH_NAME #{name}"
     end
     if title
       title = title.dump.sub(/\\#/, '#')