[PATCH v2 0/5] Fix some fast-import parsing issues

This series fixes a few issues with parsing in fast-import, dating back to git-2.6.0. The only change since v1 is removing the RFC label; sadly, no one commented on the first round.

Text from my original submission:

The point behind this series is that fast-import somehow mishandled get-mark directives after empty orphan commits. Digging into it, I think it was caused by following a precedent set by a somewhat unsafe implementation of trying to allow cat-blob directives to appear in the middle of a commit. My spelunking showed the following commits seemed to be the most relevant as to how we got to the current state:

    777f80d7429b ("fast-import: Allow cat-blob requests at arbitrary
                 points in stream", 2010-11-28)
    8dc6a373d201 ("fast-import: add 'ls' command", 2010-12-02)
    97313bef2a16 ("fast-import: use skip_prefix for parsing input",
                  2014-06-18)
    28c7b1f7b7b7 ("fast-import: add a get-mark command", 2015-07-01)

I have a few patches that fix the issue and I think make the parser more robust against future issues in a way that I think is safe enough for backward compatibility, but "backward compatible enough" might concern some folks; if so, please take a look at patches 4 and 5.

Elijah Newren (5):
  t9300: demonstrate bug with get-mark and empty orphan commits
  git-fast-import.txt: fix wording about where ls command can appear
  fast-import: check most prominent commands first
  fast-import: only allow cat-blob requests where it makes sense
  fast-import: fix erroneous handling of get-mark with empty orphan
    commits

 Documentation/git-fast-import.txt | 22 +++++++++---------
 fast-import.c                     | 31 ++++++++++++++------------
 t/t9300-fast-import.sh            | 37 +++++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+), 24 deletions(-)