config: move the option to mmap rev branch cache in the storage section

See previous commit for rational.

mercurial/branchmap.py

@@ -732,7 +732,7 b' class revbranchcache:'
 
         if self._names:
             try:
-                if repo.ui.configbool(b'format', b'mmap-revbranchcache'):
+                if repo.ui.configbool(b'storage', b'revbranchcache.mmap'):
                     with repo.cachevfs(_rbcrevs) as fp:
                         data = util.buffer(util.mmapread(fp))
                 else:

mercurial/configitems.toml

@@ -2132,6 +2132,11 b' experimental = true # experimental as l'
 
 [[items]]
 section = "storage"
+name = "revbranchcache.mmap"
+default = true
+
+[[items]]
+section = "storage"
 name = "new-repo-backend"
 default = "revlogv1"
 experimental = true
@@ -2935,8 +2940,3 b' section = "blackbox"'
 name = "date-format"
 default = ""
 in_core_extension = "blackbox"
-
-[[items]]
-section = "format"
-name = "mmap-revbranchcache"
-default = false

tests/test-branches.t

@@ -2,8 +2,8 b''
 
 #if mmap
   $ cat <<EOF >> $HGRCPATH
-  > [format]
-  > mmap-revbranchcache=true
+  > [storage]
+  > revbranchcache.mmap=true
   > EOF
 #endif