bash upgrade 3.2_048 -> 4.0_028 breaks the source command

[Miklos Vajna]

Configuration Information [Automatically generated, do not change]:
Machine: i686
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i686'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-frugalware-linux-gnu'
-DCONF_VENDOR='frugalware' -DLOCALEDIR='/usr/share/locale'
-DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib
-march=i686 -mtune=generic -O2 -pipe -fno-strict-aliasing
uname output: Linux dreamnetwork 2.6.30-fw1 #1 SMP PREEMPT Sun Jun 14
16:53:51 CEST 2009 i686 GNU/Linux
Machine Type: i686-frugalware-linux-gnu

Bash Version: 4.0
Patch Level: 28
Release Status: release

Description:
        In the current directory create an empty file 'foo'. Then the
        following will fail:

        $ sh -c 'ls foo;. foo'
        foo
        sh: line 0: .: foo: file not found

        This works fine with version 3.2, patchlevel 48.

Repeat-By:
        sh -c 'touch foo;ls foo;. foo'