automake is confused by variable and target with same name

[Kevin Dalley <kevind@rahul.net>]

A Debian user of automake has noticed the following problem in
automake-1.4.

If Makefile.am contains a variable and a target which have the
same name, Automake erroneously defines the variable as 1 in
Makefile.in.

Here's a simple test case:

kalle@PC486:/tmp/automake-bug$ ls -l
total 2
-rw-rw-r--   1 kalle    kalle          42 Mar 24 20:55 Makefile.am
-rw-rw-r--   1 kalle    kalle          76 Mar 24 20:54 configure.in
kalle@PC486:/tmp/automake-bug$ cat Makefile.am
some_file = bug.c
some_file: $(some_file)
kalle@PC486:/tmp/automake-bug$ cat configure.in
AC_INIT(configure.in)
AM_INIT_AUTOMAKE(automake-bug, 0)
AC_OUTPUT(Makefile)
kalle@PC486:/tmp/automake-bug$ automake --foreign --add-missing
automake: configure.in: installing `./install-sh'
automake: configure.in: installing `./mkinstalldirs'
automake: configure.in: installing `./missing'
kalle@PC486:/tmp/automake-bug$ grep -n -3 some_file Makefile.in
58-PRE_UNINSTALL = :
59-POST_UNINSTALL = :
60-
61:some_file = 1
62-mkinstalldirs = $(SHELL) $(top_srcdir)/mkinstalldirs
63-CONFIG_CLEAN_FILES = 
64-DIST_COMMON =  Makefile.am Makefile.in configure configure.in install-sh \
--
205-distclean-generic clean-generic maintainer-clean-generic clean \
206-mostlyclean distclean maintainer-clean
207-
208:some_file: $(some_file)
209-
210-# Tell versions [3.59,3.63) of GNU make to not export all variables.
211-# Otherwise a system limit (for SysV at least) may be exceeded.
kalle@PC486:/tmp/automake-bug$