gnu: libgit2@1.8: Fix use of uninitialized value.

* gnu/packages/patches/libgit2-uninitialized-proxy-settings.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/version-control.scm (libgit2-1.8)[source]: Use it.

Change-Id: I6b0f009d352ddadfcc57b945baea0dcc1bac0589

gnu/local.mk

@@ -1632,6 +1632,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/libgda-fix-missing-initialization.patch	\
   %D%/packages/patches/libgda-skip-postgresql-tests.patch	\
   %D%/packages/patches/libgit2-mtime-0.patch			\
+  %D%/packages/patches/libgit2-uninitialized-proxy-settings.patch	\
   %D%/packages/patches/libgnome-encoding.patch			\
   %D%/packages/patches/libgnomeui-utf8.patch			\
   %D%/packages/patches/libgrss-CVE-2016-2001.patch		\

gnu/packages/patches/libgit2-uninitialized-proxy-settings.patch

@@ -0,0 +1,19 @@
+Fix use of uninitialized value in the http-parser backend, a bug introduced
+in libgit2 1.8.1:
+
+  https://github.com/libgit2/libgit2/pull/6870
+
+This code is exercised by 'tests/proxy.scm' in Guile-Git.
+
+diff --git a/src/libgit2/transports/httpparser.c b/src/libgit2/transports/httpparser.c
+index 50ba6d2e0..1f0e65372 100644
+--- a/src/libgit2/transports/httpparser.c
++++ b/src/libgit2/transports/httpparser.c
+@@ -71,6 +71,7 @@ size_t git_http_parser_execute(
+ {
+ 	struct http_parser_settings settings_proxy;
+ 
++	settings_proxy.on_status = NULL;
+ 	settings_proxy.on_message_begin = parser->settings.on_message_begin ? on_message_begin : NULL;
+ 	settings_proxy.on_url = parser->settings.on_url ? on_url : NULL;
+ 	settings_proxy.on_header_field = parser->settings.on_header_field ? on_header_field : NULL;

gnu/packages/version-control.scm

@@ -1082,6 +1082,8 @@ write native speed custom Git applications in any language with bindings.")
               (sha256
                (base32
                 "1mh55804cvxl2cyl4clinajzgfn3zmlhacnv1pdvdj4w6z2w4si7"))
+              (patches
+               (search-patches "libgit2-uninitialized-proxy-settings.patch"))
 	      (snippet
                '(begin
                   (for-each delete-file-recursively