Work around gpg-agent issues in the test suite

GnuPG2 requires gpg-agent and tries to start it on demand.  The agent
uses a socket for communication and the path to this socket must be
shorter than sun_path [108 characters, per unix(7)].

Adjust the location of the temporary directories used by the test suite
by passing the --root option via GIT_TEST_OPTS.

One potential downside to this is that we use mktemp to create the
directory and this will differ between builds.  If/when we want to make
our builds entirely reproducible we will need to revisit this.  With
luck, gnupg will be better behaved by that time¹.

An alternate solution I tested was to rename the two problematic tests
(t5573 and t7612).  This is a brittle solution as new tests may be added
which cause the same path length issue for gpg-agent.

Also drop the redundant killing of gpg-agent.  This doesn't break
anything but it can only slow the test suite (however slightly).

¹ A ticket was filed to improve gpg-agent's handling of long paths in
  GNUPGHOME (but it's nearly 2 years old): https://dev.gnupg.org/T2964.

git.spec

@@ -778,6 +778,14 @@ export GIT_TEST_GIT_DAEMON=true
 export GIT_TEST_HTTPD=true
 export GIT_TEST_SVNSERVE=true
 
+# Create tmpdir for test output and update GIT_TEST_OPTS
+# Also update GIT-BUILD-OPTIONS to keep make from any needless rebuilding
+testdir=$(mktemp -d -p /tmp git-t.XXXX)
+sed -i "s@^GIT_TEST_OPTS = .*@& --root=$testdir@" config.mak
+touch -r GIT-BUILD-OPTIONS ts
+sed -i "s@\(GIT_TEST_OPTS='.*\)'@\1 --root=$testdir'@" GIT-BUILD-OPTIONS
+touch -r ts GIT-BUILD-OPTIONS
+
 # Run the tests
 make test || ./print-failed-test-output
 
@@ -787,6 +795,9 @@ mv netrc contrib/credential/
 make -C contrib/credential/netrc/ test || \
 make -C contrib/credential/netrc/ testverbose
 
+# Clean up test dir
+rmdir --ignore-fail-on-non-empty "$testdir"
+
 %if %{use_systemd}
 %post daemon
 %systemd_post git@.service
@@ -936,6 +947,7 @@ make -C contrib/credential/netrc/ testverbose
 - Add additional BuildRequires for i18n locales used in tests
 - Replace gitweb home-link with inline sed
 - Add gnupg2-smime and perl JSON BuildRequires for tests
+- Work around gpg-agent issues in the test suite
 
 * Thu Jan 31 2019 Fedora Release Engineering <releng@fedoraproject.org> - 2.20.1-1.1
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_30_Mass_Rebuild