config: also allow escaping outside of a quoted string

This limitation was a misparsing of the documentation.

src/config_file.c

@@ -1157,12 +1157,6 @@ static char *fixup_line(const char *ptr, int quote_count)
 				*out++ = '\\';
 				goto out;
 			}
-			/* otherwise, the backslash must be inside quotes */
-			if ((quote_count % 2) == 0) {
-				git__free(str);
-				giterr_set(GITERR_CONFIG, "Invalid escape at %s", ptr);
-				return NULL;
-			}
 			if ((esc = strchr(escapes, *ptr)) != NULL) {
 				*out++ = escaped[esc - escapes];
 			} else {

tests-clar/config/read.c

@@ -179,6 +179,18 @@ void test_config_read__prefixes(void)
 	git_config_free(cfg);
 }
 
+void test_config_read__escaping_quotes(void)
+{
+	git_config *cfg;
+	const char *str;
+
+	cl_git_pass(git_config_open_ondisk(&cfg, cl_fixture("config/config13")));
+	cl_git_pass(git_config_get_string(cfg, "core.editor", &str));
+	cl_assert(strcmp(str, "\"C:/Program Files/Nonsense/bah.exe\" \"--some option\"") == 0);
+
+	git_config_free(cfg);
+}
+
 #if 0
 
 BEGIN_TEST(config10, "a repo's config overrides the global config")