store: refactor space delimited list to proper data structure

There is no good reason why are having a space delimited list and then using
`.split()` to get the actual list. Let's convert this into a proper collection.

Differential Revision: https://phab.mercurial-scm.org/D8908

mercurial/store.py

@@ -373,10 +373,18 b' def _calcmode(vfs):'
     return mode
 
 
-_data = (
-    b'bookmarks narrowspec data meta 00manifest.d 00manifest.i'
-    b' 00changelog.d 00changelog.i phaseroots obsstore'
-)
+_data = [
+    b'bookmarks',
+    b'narrowspec',
+    b'data',
+    b'meta',
+    b'00manifest.d',
+    b'00manifest.i',
+    b'00changelog.d',
+    b'00changelog.i',
+    b'phaseroots',
+    b'obsstore',
+]
 
 
 def isrevlog(f, kind, st):
@@ -447,7 +455,7 b' class basicstore(object):'
             yield x
 
     def copylist(self):
-        return [b'requires'] + _data.split()
+        return [b'requires'] + _data
 
     def write(self, tr):
         pass
@@ -494,9 +502,7 b' class encodedstore(basicstore):'
         return self.path + b'/' + encodefilename(f)
 
     def copylist(self):
-        return [b'requires', b'00changelog.i'] + [
-            b'store/' + f for f in _data.split()
-        ]
+        return [b'requires', b'00changelog.i'] + [b'store/' + f for f in _data]
 
 
 class fncache(object):
@@ -686,12 +692,20 b' class fncachestore(basicstore):'
 
     def copylist(self):
         d = (
-            b'bookmarks narrowspec data meta dh fncache phaseroots obsstore'
-            b' 00manifest.d 00manifest.i 00changelog.d 00changelog.i'
+            b'bookmarks',
+            b'narrowspec',
+            b'data',
+            b'meta',
+            b'dh',
+            b'fncache',
+            b'phaseroots',
+            b'obsstore',
+            b'00manifest.d',
+            b'00manifest.i',
+            b'00changelog.d',
+            b'00changelog.i',
         )
-        return [b'requires', b'00changelog.i'] + [
-            b'store/' + f for f in d.split()
-        ]
+        return [b'requires', b'00changelog.i'] + [b'store/' + f for f in d]
 
     def write(self, tr):
         self.fncache.write(tr)