Move cmdtable and reposetup handling out of extensions.py
A new function (extensions.extensions) allows the code that is
interested in those attributes to handle them directly.
This allows some cleanups of extensions.py. Notably, we can
remove the extensions.commandtable hack.
It also makes it easier to add standard extension attributes,
like a "hgwebsetup" function or a "helptable" dict that augments
the data in help.py, etc.
#!/bin/sh
echo "[extensions]" >> $HGRCPATH
echo "fetch=" >> $HGRCPATH
hg init a
echo a > a/a
hg --cwd a commit -d '1 0' -Ama
hg clone a b
hg clone a c
echo b > a/b
hg --cwd a commit -d '2 0' -Amb
hg --cwd a parents -q
echo % should pull one change
hg --cwd b fetch ../a
hg --cwd b parents -q
echo c > c/c
hg --cwd c commit -d '3 0' -Amc
hg --cwd c fetch -d '4 0' -m 'automated merge' ../a
ls c