revlog: factor out _maxinline global.

This lets us change the threshold at which a *.d file will be split
out, which should make it much easier to construct test cases that
probe revlogs with a separate data file.
(issue2137)

mercurial/revlog.py

@@ -33,6 +33,8 b' REVLOG_DEFAULT_VERSION = REVLOG_DEFAULT_'
 
 _prereadsize = 1048576
 
+_maxinline = 131072                     # max size of revlog with inline data
+
 RevlogError = error.RevlogError
 LookupError = error.LookupError
 
@@ -1010,7 +1012,7 b' class revlog(object):'
         return text
 
     def checkinlinesize(self, tr, fp=None):
-        if not self._inline or (self.start(-2) + self.length(-2)) < 131072:
+        if not self._inline or (self.start(-2) + self.length(-2)) < _maxinline:
             return
 
         trinfo = tr.find(self.indexfile)