Catch HTTPException when reading from remote http repository. If the server dies very early, an httplib.IncompleteRead exception may be raised, because httplib can't read a single byte. Catching all HTTPException subclasses here will prevent ugly backtraces for similar things, too.

adding foo
adding bomb
adding a.c
adding dir/a.o
adding dir/b.o
! a.c
! dir/a.o
! dir/b.o
? .hgignore
a.c: unsupported file type (type is fifo)
! a.c