Description of problem:
in spec files, lines starting with '#' should be treated as comments and have no influence on the build process. However, this is not always the case. 

Version-Release number of selected component (if applicable):
RPM-Version 4.8.0
RPM-Version 4.7.2
(probably others as well)

How reproducible:


Steps to Reproduce:
1. create a spec file test.spec:

# test.spec
%{!?version: %define version 1.0}
%{!?name: %define name test}
%{!?release: %define release 1.0}
# %define is_client nothing  # this line is commented out

%{!?is_client: %define is_client 1}

Summary: Test of the rpm build system
Name: %{name}
Version: %{version}
Release: %{release}
License: GPL
Provides: %{name} = %{version}

%description
Test of the rpm build system


%prep
echo "the value of is_client is --%{is_client}--"


2. run rpmbuild -ba test.spec


Actual results:

rpmbuild -ba /usr/src/rpmbuild/SPECS/test.spec 
Ausführung(%prep): /bin/sh -e /var/tmp/rpm-tmp.enFbre
+ umask 022
+ cd /usr/src/rpmbuild/BUILD
+ echo the value of is_client is --nothing  # this line is commented out--
the value of is_client is --nothing  # this line is commented out--
+ exit 0
Prüfe auf nicht gepackte Datei(en): /usr/lib/rpm/check-files /usr/src/rpmbuild/BUILDROOT/test-1.0-1.0.i386
Erstellt: /usr/src/rpmbuild/SRPMS/test-1.0-1.0.src.rpm


Expected results:

Ausführung(%prep): /bin/sh -e /var/tmp/rpm-tmp.lFcTLx
+ umask 022
+ cd /usr/src/rpmbuild/BUILD
+ echo the value of is_client is --1--
the value of is_client is --1--
+ exit 0
Prüfe auf nicht gepackte Datei(en): /usr/lib/rpm/check-files /usr/src/rpmbuild/BUILDROOT/test-1.0-1.0.i386
Erstellt: /usr/src/rpmbuild/SRPMS/test-1.0-1.0.src.rpm

Additional info:
the value should be 1 in this case (which one could use for instance in a %if statement). It should not be influenced by something on a line starting with '#'