From: David Bremner <bremner@debian.org>

Current code does not distinguish between an empty string in the
NMBPREFIX environment variable and the variable being undefined. This
makes it impossible to define an empty prefix, if, e.g. somebody wants
to dump all of their tags with nmbug.
---
 devel/nmbug/nmbug |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/devel/nmbug/nmbug b/devel/nmbug/nmbug
index b9c70e4..90d98b6 100755
--- a/devel/nmbug/nmbug
+++ b/devel/nmbug/nmbug
@@ -13,7 +13,7 @@ my $NMBGIT = $ENV{NMBGIT} || $ENV{HOME}.'/.nmbug';
 
 $NMBGIT .= '/.git' if (-d $NMBGIT.'/.git');
 
-my $TAGPREFIX = $ENV{NMBPREFIX} || 'notmuch::';
+my $TAGPREFIX = defined($ENV{NMBPREFIX}) ? $ENV{NMBPREFIX} : 'notmuch::';
 
 # for encoding
 
-- 
1.7.10.4