git-bundle: prevent overwriting existing bundles
git-bundle: prevent overwriting existing bundles

Not only does it prevent accidentally losing older bundles, but it
also fixes a subtle bug: when writing into an existing bundle,
git-pack-objects would not truncate the bundle. Therefore,
fetching from the bundle would trigger an error in unpack-objects:
"fatal: pack has junk at the end".

Signed-off-by: Johannes Schindelin <53fb8db7833fca1e1746dd8592f61048d350f64c@gmx.de>
Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git