builddependencies: share code between single- and multi-successor cases
The two cases now have more similar structure ("if succ in revs:
dependencies[r].add(succ)"), so let's share the code so it doesn't
start drifting apart again.
import hghave
@hghave.check("docgraph-ext", "Extension to generate graph from repository")
def docgraph():
try:
import hgext.docgraph
hgext.docgraph.cmdtable # trigger import
except ImportError:
try:
import hgext3rd.docgraph
hgext3rd.docgraph.cmdtable # trigger import
except ImportError:
return False
return True