obsstore: add relevantmarkers method
We add a ``relevantmarkers`` method to fetch all markers that seem relevant to a
set of nodes. See function documentation about how this set is computed. This
will let us exchange only the markers that seem "relevant" to the set of
changesets related to a push or a pull.
The approach used to define "relevant" has been successfully tested in evolve
for 6 months.
#!/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