From: Oliver Beattie <oliver@obeattie.com>
Date: Thu, 5 Sep 2013 16:03:24 +0000 (+0100)
Subject: More informative error message when trying to retrieve a single head, but there are... 
X-Git-Tag: rel_0_6_1~31^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a56325915f8a7d88798253c27b7b69eb7cf931df;p=thirdparty%2Fsqlalchemy%2Falembic.git

More informative error message when trying to retrieve a single head, but there are multiple.
---

diff --git a/alembic/script.py b/alembic/script.py
index 77366e30..d019480e 100644
--- a/alembic/script.py
+++ b/alembic/script.py
@@ -246,6 +246,11 @@ class ScriptDirectory(object):
         """
         current_heads = self.get_heads()
         if len(current_heads) > 1:
+            raise util.CommandError('Only a single head is supported. The '
+                'script directory has multiple heads (due to branching), which'
+                'must be resolved by manually editing the revision files to '
+                'form a linear sequence. Run `alembic branches` to see the '
+                'divergence(s).')
             raise util.CommandError("Only a single head supported so far...")
         if current_heads:
             return current_heads[0]