tests/svn-safe-append.py

largefiles: improve comments, internal docstrings

- fix some ungrammatical/unclear/incorrect comments/docstrings
- rewrite some really unclear comments/docstrings
- make formatting/style more consistent with the rest of Mercurial
  (lowercase without period unless it's really multiple sentences)
- wrap to 75 columns
- always say "largefile(s)", not "lfile(s)" (or "big files")
- one space between sentences, not two

#!/usr/bin/env python

__doc__ = """Same as `echo a >> b`, but ensures a changed mtime of b.
Without this svn will not detect workspace changes."""

import sys, os

text = sys.argv[1]
fname = sys.argv[2]

f = open(fname, "ab")
try:
    before = os.fstat(f.fileno()).st_mtime
    f.write(text)
    f.write("\n")
finally:
    f.close()
inc = 1
now = os.stat(fname).st_mtime
while now == before:
    t = now + inc
    inc += 1
    os.utime(fname, (t, t))
    now = os.stat(fname).st_mtime