view tests/test-race @ 7654:816b708f23af

store all heads of a branch in the branch cache

All heads of branches will be stored in a new cache file 'branchheads.cache'
within the .hg directory. The old 'branch.cache' file from older versions
will be ignored.

The new cache contents are formatted line-by-line as '{node} {branchtag}\n'.
This is the same as the previous format. Now, every head is recorded in
an oldest -> tipmost order.

The localrepo.branchheads function is reworked to use the data from the cache.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m test

# do we ever miss a sub-second change?
for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
    hg co -qC 0
    echo b > a
    hg st
done