dpkg: Use ohshit() instead of internerr() for unhandled dpkg-split exit codes

If dpkg-split exits with an unhandled exit code we should not abort
dpkg, we should just handle the error in the same way we handle errors
from debsig-verify or dpkg-deb.

Closes: #812679

debian/changelog

@@ -10,6 +10,8 @@ dpkg (1.18.5) UNRELEASED; urgency=medium
   * Print the archive filename when dpkg cannot access it.
   * Check that all passed archive filenames to dpkg exist before queueing them.
     Closes: #809963
+  * Use ohshit() instead of internerr() for unhandled dpkg-split exit codes.
+    (i.e. do not abort). Closes: #812679
   * Perl modules:
     - Add new CTRL_REPO_RELEASE control block type to Dpkg::Control.
     - Add new CTRL_COPYRIGHT_HEADER, CTRL_COPYRIGHT_FILES and

src/unpack.c

@@ -120,7 +120,7 @@ deb_reassemble(const char **filename, const char **pfilename)
     /* No, it wasn't a part. */
     break;
   default:
-    internerr("unexpected exit status %d from %s", status, SPLITTER);
+    ohshit(_("subprocess %s returned error exit status %d"), SPLITTER, status);
   }
 
   return true;