Steps to reproduce:
1. Phabricator install connected to jira
2. Create a new branch, with some commits
3. On this new feature, run `arc diff` and don't specify a JIRA issue. This works fine for now.
4. Amend some commits, and run `arc diff` again. Whether or not, I specify a JIRA issue linked to it, the arc command fails.
I get an error message. The detailed trace of the arcanist functionality is:
```
(rfenv)➜ genprops git:(big_feature) arc diff --trace HEAD~3
libphutil loaded from '/Users/anirudh/opt/libphutil/src'.
arcanist loaded from '/Users/anirudh/opt/arcanist/src'.
Working Copy: Reading .arcconfig from "/Users/anirudh/jsrf/.arcconfig".
Working Copy: Path "/Users/anirudh/jsrf/tools/src/genprops" is part of `git` working copy "/Users/anirudh/jsrf".
Working Copy: Project root is at "/Users/anirudh/jsrf".
>>> [0] <conduit> conduit.connect() <bytes = 473>
>>> [1] <http> http://forge.razorflow.com/api/conduit.connect
<<< [1] <http> 1,897,945 us
<<< [0] <conduit> 1,900,990 us
>>> [2] <exec> $ git diff --no-ext-diff --no-textconv --raw 'HEAD' --
>>> [3] <exec> $ git ls-files --others --exclude-standard
>>> [4] <exec> $ git diff-files --name-only
<<< [4] <exec> 7,826 us
<<< [2] <exec> 10,443 us
<<< [3] <exec> 9,731 us
>>> [5] <event> diff.didCollectChanges <listeners = 0>
<<< [5] <event> 60 us
>>> [6] <exec> $ git merge-base 'HEAD~3' HEAD
<<< [6] <exec> 7,099 us
>>> [7] <exec> $ php '/Users/anirudh/opt/arcanist/src/../scripts/arcanist.php' --recon diff --no-diff '--ansi' 'HEAD~3'
>>> [8] <exec> $ git log --first-parent --format=medium '5eb4c272422d3412dbbcc1251527179496c9a751'..HEAD
<<< [8] <exec> 9,175 us
>>> [9] <conduit> differential.query() <bytes = 274>
>>> [10] <http> http://forge.razorflow.com/api/differential.query
<<< [10] <http> 555,634 us
<<< [9] <conduit> 555,874 us
>>> [11] <exec> $ git rev-parse --git-dir
<<< [11] <exec> 7,578 us
You have a saved revision message in '.git/arc/create-message'.
Message begins:
improved documentation
You can use this message, or discard it.
Do you want to use this message? [Y/n] n
>>> [12] <exec> $ git log 'HEAD' --not '5eb4c272422d3412dbbcc1251527179496c9a751
' --format='%H%x01%T%x01%P%x01%at%x01%an%x01%aE%x01%s%x01%s%n%n%b%x02' --
<<< [12] <exec> 9,508 us
>>> [13] <conduit> differential.parsecommitmessage() <bytes = 479>
>>> [14] <http> http://forge.razorflow.com/api/differential.parsecommitmessage
<<< [14] <http> 351,428 us
<<< [13] <conduit> 351,698 us
>>> [15] <conduit> differential.parsecommitmessage() <bytes = 233>
>>> [16] <http> http://forge.razorflow.com/api/differential.parsecommitmessage
<<< [16] <http> 307,815 us
<<< [15] <conduit> 308,165 us
>>> [17] <conduit> differential.parsecommitmessage() <bytes = 225>
>>> [18] <http> http://forge.razorflow.com/api/differential.parsecommitmessage
<<< [18] <http> 304,506 us
<<< [17] <conduit> 304,867 us
>>> [19] <event> diff.willBuildMessage <listeners = 0>
<<< [19] <event> 114 us
>>> [20] <conduit> differential.getcommitmessage() <bytes = 592>
>>> [21] <http> http://forge.razorflow.com/api/differential.getcommitmessage
<<< [21] <http> 307,105 us
<<< [20] <conduit> 307,400 us
>>> [22] <exec> $ git branch --no-color
<<< [22] <exec> 8,368 us
>>> [23] <exec> $ vim '/var/folders/b2/hxy_bv2x51987m4bjx35bjd40000gn/T/edit.bl0xnvsk1goog8kg/new-commit'
<<< [23] <exec> 11,085,808 us
>>> [24] <conduit> differential.parsecommitmessage() <bytes = 594>
>>> [25] <http> http://forge.razorflow.com/api/differential.parsecommitmessage
<<< [25] <http> 1,800,487 us
<<< [24] <conduit> 1,800,817 us
>>> [26] <conduit> differential.query() <bytes = 178>
>>> [27] <http> http://forge.razorflow.com/api/differential.query
>>> [28] <conduit> user.query() <bytes = 215>
>>> [29] <http> http://forge.razorflow.com/api/user.query
<<< [27] <http> 615,658 us
<<< [26] <conduit> 627,300 us
<<< [29] <http> 1,227,595 us
<<< [28] <conduit> 1,227,904 us
>>> [30] <event> diff.didBuildMessage <listeners = 0>
<<< [30] <event> 54 us
>>> [31] <conduit> differential.getcommitmessage() <bytes = 230>
>>> [32] <http> http://forge.razorflow.com/api/differential.getcommitmessage
<<< [32] <http> 430,164 us
<<< [31] <conduit> 430,414 us
>>> [33] <conduit> differential.parsecommitmessage() <bytes = 630>
>>> [34] <http> http://forge.razorflow.com/api/differential.parsecommitmessage
<<< [34] <http> 2,029,479 us
<<< [33] <conduit> 2,029,716 us
<<< [7] <exec> 20,848,789 us
[2014-03-06 08:02:56] EXCEPTION: (ArcanistDifferentialCommitMessageParserException) Invalid or missing field 'JIRA Issues': Some JIRA issues could not be loaded. They may not exist, or you may not have permission to view them: #, Tip:, Use, "Depends, on, D123", in, your, summary, to, mark, a, dependency, between, #, revisions. at [/Users/anirudh/opt/arcanist/src/differential/ArcanistDifferentialCommitMessage.php:79]
#0 ArcanistDifferentialCommitMessage::pullDataFromConduit(Object ConduitClient) called at [/Users/anirudh/opt/arcanist/src/workflow/ArcanistDiffWorkflow.php:750]
#1 ArcanistDiffWorkflow::buildRevisionFromCommitMessage(Object ArcanistDifferentialCommitMessage) called at [/Users/anirudh/opt/arcanist/src/workflow/ArcanistDiffWorkflow.php:465]
#2 ArcanistDiffWorkflow::run() called at [/Users/anirudh/opt/arcanist/scripts/arcanist.php:321]
```