largefiles: when setting/clearing x bit on largefiles, don't change other bits

It is only the X bit that it matters to copy from the standin to the largefile
in the working directory. While it generally doesn't do any harm to copy the
whole mode, it is also "wrong" to copy more than the X bit we care about. It
can make a difference if someone should try to handle largefiles differently,
such as marking them read-only.

Thus, do similar to what utils.setflags does and set the X bit where there are
R bits and obey umask.

hgext/largefiles/lfcommands.py

@@ -515,9 +515,13 b' def updatelfiles(ui, repo, filelist=None'
             rellfile = lfile
             relstandin = lfutil.standin(lfile)
             if wvfs.exists(relstandin):
-                mode = wvfs.stat(relstandin).st_mode
-                if mode != wvfs.stat(rellfile).st_mode:
-                    wvfs.chmod(rellfile, mode)
+                standinexec = wvfs.stat(relstandin).st_mode & 0o100
+                st = wvfs.stat(rellfile).st_mode
+                if standinexec != st & 0o100:
+                    st &= ~0o111
+                    if standinexec:
+                        st |= (st >> 2) & 0o111 & ~util.umask
+                    wvfs.chmod(rellfile, st)
                     update1 = 1
 
             updated += update1