tests/test-debugindexdot

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

# Just exercize debugindexdot
# Create a short file history including a merge.
hg init t
cd t
echo a > a
hg ci -qAm t1 -d '0 0'
echo a >> a
hg ci -m t2 -d '1 0'
hg up -qC 0
echo b >> a
hg ci -m t3 -d '2 0'
HGMERGE=true hg merge -q
hg ci -m merge -d '3 0'

hg debugindexdot .hg/store/data/a.i