phases: move root phase assignment to it's own function
This moves the initial root phase assignment to it's own function. Future
patches which make phase calculations lazy will use this function to pre-fill
certain phases which can be deduced from the roots.
#require test-repo
Enable obsolescence to avoid the warning issue when obsmarker are found
$ cat > obs.py << EOF
> import mercurial.obsolete
> mercurial.obsolete._enabled = True
> EOF
$ echo '[extensions]' >> $HGRCPATH
$ echo "obs=${TESTTMP}/obs.py" >> $HGRCPATH
Go back in the hg repo
$ cd $TESTDIR/..
$ for node in `hg log --rev 'draft() and ::.' --template '{node|short}\n'`; do
> hg export $node | contrib/check-commit > ${TESTTMP}/check-commit.out
> if [ $? -ne 0 ]; then
> echo "Revision $node does not comply to commit message rules"
> echo '------------------------------------------------------'
> cat ${TESTTMP}/check-commit.out
> echo
> fi
> done