config: add test cases for empty value and no value config variables.

The tests in 't1300-repo-config.sh' did not check what happens when
an empty value like the following is used in the config file:

[emptyvalue]
	variable =

Also it was not checked that a variable with no value like the
following:

[novalue]
	variable

gives a boolean "true" value, while an ampty value gives a boolean
"false" value.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1300-repo-config.sh

@@ -297,17 +297,40 @@ test_expect_success '--add' \
 cat > .git/config << EOF
 [novalue]
 	variable
+[emptyvalue]
+	variable =
 EOF
 
 test_expect_success 'get variable with no value' \
 	'git config --get novalue.variable ^$'
 
+test_expect_success 'get variable with empty value' \
+	'git config --get emptyvalue.variable ^$'
+
 echo novalue.variable > expect
 
 test_expect_success 'get-regexp variable with no value' \
 	'git config --get-regexp novalue > output &&
 	 cmp output expect'
 
+echo 'emptyvalue.variable ' > expect
+
+test_expect_success 'get-regexp variable with empty value' \
+	'git config --get-regexp emptyvalue > output &&
+	 cmp output expect'
+
+echo true > expect
+
+test_expect_success 'get bool variable with no value' \
+	'git config --bool novalue.variable > output &&
+	 cmp output expect'
+
+echo false > expect
+
+test_expect_success 'get bool variable with empty value' \
+	'git config --bool emptyvalue.variable > output &&
+	 cmp output expect'
+
 git config > output 2>&1
 
 test_expect_success 'no arguments, but no crash' \