cache: create `cache` directory at init time

The cache directory will be needed very quickly, so it seems simpler to create
it early to make sure it has the same owner and permission than the other
directory in the repository.

mercurial/localrepo.py

@@ -3010,6 +3010,8 b' def createrepository(ui, path, createopt'
         wdirvfs.makedirs()
 
     hgvfs.makedir(notindexed=True)
+    if 'sharedrepo' not in createopts:
+        hgvfs.mkdir(b'cache')
 
     if b'store' in requirements and 'sharedrepo' not in createopts:
         hgvfs.mkdir(b'store')

tests/test-empty.t

@@ -20,6 +20,7 b' Check the basic files created:'
 
   $ ls .hg
   00changelog.i
+  cache
   requires
   store
 

tests/test-inherit-mode.t

@@ -42,7 +42,7 b' just in case somebody has a strange $TMP'
   $ hg init repo
   $ cd repo
 
-  $ chmod 0770 .hg/store
+  $ chmod 0770 .hg/store .hg/cache
 
 before commit
 store can be written by the group, other files cannot
@@ -51,6 +51,7 b' store is setgid'
   $ "$PYTHON" ../printmodes.py .
   00700 ./.hg/
   00600 ./.hg/00changelog.i
+  00770 ./.hg/cache/
   00600 ./.hg/requires
   00770 ./.hg/store/
 
@@ -116,6 +117,7 b' group can write everything'
   $ "$PYTHON" ../printmodes.py ../push
   00770 ../push/.hg/
   00660 ../push/.hg/00changelog.i
+  00770 ../push/.hg/cache/
   00660 ../push/.hg/requires
   00770 ../push/.hg/store/