Make pg8000 version detection more robust

pg8000 uses Versioneer, which means that development versions have
version strings that don't fit into the dotted triple number format.
Released versions will always fit the triple format though.

1 files changed, 11 insertions, 6 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/pg8000.py b/lib/sqlalchemy/dialects/postgresql/pg8000.py
index a76787016..17d83fa61 100644
--- a/lib/sqlalchemy/dialects/postgresql/pg8000.py
+++ b/lib/sqlalchemy/dialects/postgresql/pg8000.py
@@ -71,6 +71,7 @@ from ... import types as sqltypes
 from .base import (
     PGDialect, PGCompiler, PGIdentifierPreparer, PGExecutionContext,
     _DECIMAL_TYPES, _FLOAT_TYPES, _INT_TYPES)
+import re
 
 
 class _PGNumeric(sqltypes.Numeric):
@@ -151,15 +152,19 @@ class PGDialect_pg8000(PGDialect):
         self.client_encoding = client_encoding
 
     def initialize(self, connection):
-        if self.dbapi and hasattr(self.dbapi, '__version__'):
-            self._dbapi_version = tuple([
-                int(x) for x in
-                self.dbapi.__version__.split(".")])
-        else:
-            self._dbapi_version = (99, 99, 99)
         self.supports_sane_multi_rowcount = self._dbapi_version >= (1, 9, 14)
         super(PGDialect_pg8000, self).initialize(connection)
 
+    @util.memoized_property
+    def _dbapi_version(self):
+        if self.dbapi and hasattr(self.dbapi, '__version__'):
+            return tuple(
+                [
+                    int(x) for x in re.findall(
+                        r'(\d+)(?:[-\.]?|$)', self.dbapi.__version__)])
+        else:
+            return (99, 99, 99)
+
     @classmethod
     def dbapi(cls):
         return __import__('pg8000')