libphutil loaded from '/home/thiblahute/devel/libphutil/src'.
arcanist loaded from '/home/thiblahute/devel/arcanist/src'.
Config: Reading user configuration file "/home/thiblahute/.arcrc"...
Config: Did not find system configuration at "/etc/arcconfig".
Working Copy: Unable to find .arcconfig in any of these locations: /home/thiblahute/devel/pitivi/1.0-uninstalled/gst-editing-services/.arcconfig.
Working Copy: Path "/home/thiblahute/devel/pitivi/1.0-uninstalled/gst-editing-services" is part of `git` working copy "/home/thiblahute/devel/pitivi/1.0-uninstalled/gst-editing-services".
Working Copy: Project root is at "/home/thiblahute/devel/pitivi/1.0-uninstalled/gst-editing-services".
Config: Did not find local configuration at "/home/thiblahute/devel/pitivi/1.0-uninstalled/gst-editing-services/.git/arc/config".
>>> [0] <conduit> user.whoami() <bytes = 117>
>>> [1] <http> http://SOMETHING/api/user.whoami
<<< [1] <http> 4,474,917 us
<<< [0] <conduit> 4,475,120 us
>>> [2] <exec> $ git diff --no-ext-diff --no-textconv --raw 'HEAD' --
>>> [3] <exec> $ git ls-files --others --exclude-standard
<<< [3] <exec> 70,033 us
<<< [2] <exec> 86,477 us
>>> [4] <exec> $ git diff-files --name-only
<<< [4] <exec> 87,854 us
You have untracked files in this working copy.

  Working copy: /home/thiblahute/devel/pitivi/1.0-uninstalled/gst-editing-services/

  Untracked files in working copy:
    docs/design/ges-cli-formatter.md
    ges/nle/tags
    ges/tags
    raw
    tags
    test
    test.py
    test.xges
    tests/check/ges/tags
    tests/check/nle/tags
    tests/validate/scenarios/remove-last-clip.scenario
    tests/validate/tags
    tools/lex.priv_ges_parse_yy.c
    tools/parse_lex.h
    tools/tags

Since you don't have '.gitignore' rules for these files and have not listed
them in '.git/info/exclude', you may have forgotten to 'git add' them to your
commit.
>>> [5] <exec> $ git rev-parse --verify HEAD^
<<< [5] <exec> 69,755 us
>>> [6] <exec> $ git rev-parse 'HEAD'
<<< [6] <exec> 67,442 us
>>> [7] <exec> $ git log 'cd982f06d0d867a446597f043d646656e1c5be6b' --not '*' --format='%H%x01%T%x01%P%x01%at%x01%an%x01%aE%x01%s%x01%s%n%n%b%x02' --
<<< [7] <exec> 71,077 us

[2015-02-19 17:41:51] EXCEPTION: (CommandException) Command failed with error #128!
COMMAND
git log 'cd982f06d0d867a446597f043d646656e1c5be6b' --not '*' --format='%H%x01%T%x01%P%x01%at%x01%an%x01%aE%x01%s%x01%s%n%n%b%x02' --

STDOUT
(empty)

STDERR
fatal: bad revision '*'
 at [<phutil>/src/future/exec/ExecFuture.php:397]
  #0 ExecFuture::resolvex() called at [<arcanist>/src/repository/api/ArcanistRepositoryAPI.php:394]
  #1 ArcanistRepositoryAPI::execxLocal(string, PhutilCommandString, string) called at [<arcanist>/src/repository/api/ArcanistGitAPI.php:173]
  #2 ArcanistGitAPI::getLocalCommitInformation() called at [<arcanist>/src/workflow/ArcanistWorkflow.php:985]
  #3 ArcanistWorkflow::calculateShouldAmend() called at [<arcanist>/src/workflow/ArcanistWorkflow.php:973]
  #4 ArcanistWorkflow::getShouldAmend() called at [<arcanist>/src/workflow/ArcanistWorkflow.php:1050]
  #5 ArcanistWorkflow::getAskForAddPrompt(array) called at [<arcanist>/src/workflow/ArcanistWorkflow.php:1045]
  #6 ArcanistWorkflow::askForAdd(array) called at [<arcanist>/src/workflow/ArcanistWorkflow.php:864]
  #7 ArcanistWorkflow::requireCleanWorkingCopy() called at [<arcanist>/src/workflow/ArcanistDiffWorkflow.php:642]
  #8 ArcanistDiffWorkflow::runDiffSetupBasics() called at [<arcanist>/src/workflow/ArcanistDiffWorkflow.php:431]
  #9 ArcanistDiffWorkflow::run() called at [<arcanist>/scripts/arcanist.php:378]

diff --git a/src/repository/api/ArcanistGitAPI.php b/src/repository/api/ArcanistGitAPI.php
index 15850c6..efdf3fa 100644
--- a/src/repository/api/ArcanistGitAPI.php
+++ b/src/repository/api/ArcanistGitAPI.php
@@ -151,10 +151,7 @@ final class ArcanistGitAPI extends ArcanistRepositoryAPI {
         }
       }
 
-      $against = csprintf(
-        '%s --not %s',
-        $this->getHeadCommit(),
-        $this->getBaseCommit());
+      $against = csprintf( '%s', $this->getHeadCommit());
     }
 
     // NOTE: Windows escaping of "%" symbols apparently is inherently broken;