Fix Oracle buffer allocation issue.

Hopefully, at least. Closes #316.

Changes

@@ -30,6 +30,9 @@ Revision history for Perl extension App::Sqitch
        violation. Thanks to Eric Bréchemier for the suggestion (#344).
      - Moved the project to its own GitHub organization:
        https://github.com/sqitchers.
+     - Fixed likely cause of Oracle buffer allocation bug when selecting
+       timestamp strings. Thanks to @johannwilfling for the bug report and to
+       @nmaqsudov for the analysis and solution (#316).
 
 0.9997 2018-03-15T21:13:52Z
      - Fixed the Firebird engine to properly detect multiple instances of a

lib/App/Sqitch/Engine/oracle.pm

@@ -136,7 +136,7 @@ sub _log_conflicts_param {
 }
 
 sub _ts2char_format {
-    q{CAST(to_char(%1$s AT TIME ZONE 'UTC', '"year":YYYY:"month":MM:"day":DD') || to_char(%1$s AT TIME ZONE 'UTC', ':"hour":HH24:"minute":MI:"second":SS:"time_zone":"UTC"')  AS VARCHAR2(92 char))}
+    q{CAST(to_char(%1$s AT TIME ZONE 'UTC', '"year":YYYY:"month":MM:"day":DD') AS VARCHAR2(100 byte)) || CAST(to_char(%1$s AT TIME ZONE 'UTC', ':"hour":HH24:"minute":MI:"second":SS:"time_zone":"UTC"')  AS VARCHAR2(168 byte))}
 }
 
 sub _ts_default { 'current_timestamp' }

t/oracle.t

@@ -428,7 +428,7 @@ $mock_ora->unmock_all;
 # Test DateTime formatting stuff.
 ok my $ts2char = $CLASS->can('_ts2char_format'), "$CLASS->can('_ts2char_format')";
 is sprintf($ts2char->(), 'foo'),
-    q{CAST(to_char(foo AT TIME ZONE 'UTC', '"year":YYYY:"month":MM:"day":DD') || to_char(foo AT TIME ZONE 'UTC', ':"hour":HH24:"minute":MI:"second":SS:"time_zone":"UTC"')  AS VARCHAR2(92 char))},
+    q{CAST(to_char(foo AT TIME ZONE 'UTC', '"year":YYYY:"month":MM:"day":DD') AS VARCHAR2(100 byte)) || CAST(to_char(foo AT TIME ZONE 'UTC', ':"hour":HH24:"minute":MI:"second":SS:"time_zone":"UTC"')  AS VARCHAR2(168 byte))},
     '_ts2char_format should work';
 
 ok my $dtfunc = $CLASS->can('_dt'), "$CLASS->can('_dt')";