lock: don't use 'file' as a variable name

Differential Revision: https://phab.mercurial-scm.org/D3320

mercurial/lock.py

@@ -175,11 +175,11 b' class lock(object):'
 
     _host = None
 
-    def __init__(self, vfs, file, timeout=-1, releasefn=None, acquirefn=None,
+    def __init__(self, vfs, fname, timeout=-1, releasefn=None, acquirefn=None,
                  desc=None, inheritchecker=None, parentlock=None,
                  dolock=True):
         self.vfs = vfs
-        self.f = file
+        self.f = fname
         self.held = 0
         self.timeout = timeout
         self.releasefn = releasefn