git-svn: branch: avoid systematic prompt for cert/pass

Commands such as "git svn init/fetch/dcommit" do not prompt for client
certificate/password if they are stored in SVN config file.  Make
"git svn branch" consistent with the other commands, as SVN::Client is
capable of building its own authentication baton from information in the
SVN config directory.

Signed-off-by: Monard Vong <travelingsoul86@gmail.com>
Signed-off-by: Eric Wong <normalperson@yhbt.net>
git svn: info: correctly handle absolute path args

Calling "git svn info $(pwd)" would hit:
  "Reading from filehandle failed at ..."
errors due to improper prefixing and canonicalization.

Strip the toplevel path from absolute filesystem paths to ensure
downstream canonicalization routines are only exposed to paths
tracked in git (or SVN).

v2:
  Thanks to Andrej Manduch for originally noticing the issue
  and fixing my original version of this to handle
  more corner cases such as "/path/to/top/../top" and
  "/path/to/top/../top/file" as shown in the new test cases.

v3:
  Fix pathname portability problems pointed out by Johannes Sixt
  with a hint from brian m. carlson.

Cc: Johannes Sixt <j6t@kdbg.org>
Cc: "brian m. carlson" <sandals@crustytoothpaste.net>
Signed-off-by: Andrej Manduch <amanduch@gmail.com>
Signed-off-by: Eric Wong <normalperson@yhbt.net>
git-svn.txt: Remove mentions of repack options

Git no longer seems to use these flags or their associated config keys;
when they are present, git-svn outputs a message indicating that they
are being ignored.

Signed-off-by: Lawrence Velázquez <vq@larryv.me>
Signed-off-by: Eric Wong <normalperson@yhbt.net>
git svn: find-rev allows short switches for near matches

Allow -B and -A to act as short aliases for --before and --after
options respectively.  This reduces typing and hopefully allows
reuse of muscle memory for grep(1) users.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
git-svn: delay term initialization

On my Debian 7 system, this fixes annoying warnings when the output
of "git svn" commands are redirected:

    Unable to get Terminal Size. The TIOCGWINSZ ioctl didn't work.
    The COLUMNS and LINES environment variables didn't work. The
    resize program didn't work.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
describe: support the syntax "--abbrev=+"

It will print just a "+" sign appended to the found tag, if there
are commits between the tag and the supplied commit.

It's useful when you just need a simple output to know if the
supplied commit is an exact match or not.
describe: Add documentation for "--abbrev=+"