fast-import: clarify "inline" logic in file_change_m

When we read a fast-import line like:

  M 100644 :1 foo.c

we point the local object_entry variable "oe" to the object
named by the mark ":1". When the input uses the "inline"
construct, however, we do not have such an object_entry.

The current code is careful not to access "oe" in the inline
case, but we can make the assumption even more obvious (and
catch violations of it) by setting oe to NULL and adding a
comment. As a bonus, this also squelches an over-zealous gcc
-Wuninitialized warning, which means we can drop the "oe =
oe" initialization hack.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fast-import.c

@@ -2265,7 +2265,7 @@ static void file_change_m(struct branch *b)
 	const char *p = command_buf.buf + 2;
 	static struct strbuf uq = STRBUF_INIT;
 	const char *endp;
-	struct object_entry *oe = oe;
+	struct object_entry *oe;
 	unsigned char sha1[20];
 	uint16_t mode, inline_data = 0;
 
@@ -2292,6 +2292,7 @@ static void file_change_m(struct branch *b)
 		hashcpy(sha1, oe->idx.sha1);
 	} else if (!prefixcmp(p, "inline ")) {
 		inline_data = 1;
+		oe = NULL; /* not used with inline_data, but makes gcc happy */
 		p += strlen("inline");  /* advance to space */
 	} else {
 		if (get_sha1_hex(p, sha1))