largefiles: cleanup of warnings on errors getting largefiles
Especially the "no default or default-push path set in hgrc" was often very
misleading and didn't give any hint where it actually was looking.
A long error messages is better than several multi-line messages.
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved