[PATCH 5/7] Add support for gnupg < 1.4

["Tom G. Christensen" <tgc@jupiterrise.com>]

This adds an OLD_GNUPG define to the Makefile which when activated will
ensure git does not use the --keyid-format argument when calling the
'gpg' program.
This is consistent with how 'gpg' was used in git < 2.10.0 and slightly
decreases security.

Signed-off-by: Tom G. Christensen <tgc@jupiterrise.com>
---
 Makefile        | 6 ++++++
 gpg-interface.c | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/Makefile b/Makefile
index ca9f16d19..f8f585d21 100644
--- a/Makefile
+++ b/Makefile
@@ -386,6 +386,8 @@ all::
 #
 # to say "export LESS=FRX (and LV=-c) if the environment variable
 # LESS (and LV) is not set, respectively".
+#
+# Define OLD_GNUPG if you need support for gnupg < 1.4.
 
 GIT-VERSION-FILE: FORCE
 	@$(SHELL_PATH) ./GIT-VERSION-GEN
@@ -1529,6 +1531,10 @@ ifndef PAGER_ENV
 PAGER_ENV = LESS=FRX LV=-c
 endif
 
+ifdef OLD_GNUPG
+	BASIC_CFLAGS += -DOLD_GNUPG
+endif
+
 QUIET_SUBDIR0  = +$(MAKE) -C # space to separate -C and subdir
 QUIET_SUBDIR1  =
 
diff --git a/gpg-interface.c b/gpg-interface.c
index e44cc27da..57f1ea792 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c
@@ -224,7 +224,9 @@ int verify_signed_buffer(const char *payload, size_t payload_size,
 	argv_array_pushl(&gpg.args,
 			 gpg_program,
 			 "--status-fd=1",
+#ifndef OLD_GNUPG
 			 "--keyid-format=long",
+#endif
 			 "--verify", temp.filename.buf, "-",
 			 NULL);
 
-- 
2.12.2