git-phab: Add some input error checking to cherry-pick mode

cherry-pick doesn’t support tasks, so improve the error message if you
run `git phab cherry-pick T123`, rather than throwing a
phabricator.APIError which is not especially helpful.

Reviewed-by: Thibault Saunier <tsaunier@gnome.org>
Differential Revision: https://phabricator.freedesktop.org/D1239

1 files changed, 3 insertions, 0 deletions

diff --git a/git-phab b/git-phab
index 684cc92..de5be23 100755
--- a/git-phab
+++ b/git-phab
@@ -1422,6 +1422,9 @@ Paste API Token from that page and press <enter>: """ % self.phabricator_uri)
         print("Checking revision:", self.differential)
         did = self.differential.strip("D")
 
+        if not did.isdigit():
+            self.die("Invalid diff ID ‘{}’".format(self.differential))
+
         revision, diff = self.get_revision_and_diff(diff=did)
 
         if self.fetch_staging_commits(diff):