Merge branch 'maint'

* maint:
  base85: Make the code more obvious instead of explaining the non-obvious
  base85: encode_85() does not use the decode table
  base85 debug code: Fix length byte calculation
  Documentation: tiny git config manual tweaks
  Documentation: git gc packs refs by default now
  checkout -m: do not try to fall back to --merge from an unborn branch

Author: gitster

Documentation/config.txt

@@ -537,7 +537,7 @@ apply.whitespace::
 	as the '--whitespace' option. See linkgit:git-apply[1].
 
 branch.autosetupmerge::
-	Tells 'git-branch' and 'git-checkout' to setup new branches
+	Tells 'git-branch' and 'git-checkout' to set up new branches
 	so that linkgit:git-pull[1] will appropriately merge from the
 	starting point branch. Note that even if this option is not set,
 	this behavior can be chosen per-branch using the `--track`
@@ -725,7 +725,7 @@ diff.autorefreshindex::
 	contents in the work tree match the contents in the
 	index.  This option defaults to true.  Note that this
 	affects only 'git-diff' Porcelain, and not lower level
-	'diff' commands, such as 'git-diff-files'.
+	'diff' commands such as 'git-diff-files'.
 
 diff.external::
 	If this config variable is set, diff generation is not
@@ -841,8 +841,8 @@ format.pretty::
 
 format.thread::
 	The default threading style for 'git-format-patch'.  Can be
-	either a boolean value, `shallow` or `deep`.  `shallow`
-	threading makes every mail a reply to the head of the series,
+	a boolean value, or `shallow` or `deep`.  `shallow` threading
+	makes every mail a reply to the head of the series,
 	where the head is chosen from the cover letter, the
 	`\--in-reply-to`, and the first patch mail, in this order.
 	`deep` threading makes every mail a reply to the previous one.
@@ -875,15 +875,12 @@ gc.autopacklimit::
 	default	value is 50.  Setting this to 0 disables it.
 
 gc.packrefs::
-	'git-gc' does not run `git pack-refs` in a bare repository by
-	default so that older dumb-transport clients can still fetch
-	from the repository.  Setting this to `true` lets 'git-gc'
-	to run `git pack-refs`.  Setting this to `false` tells
-	'git-gc' never to run `git pack-refs`. The default setting is
-	`notbare`. Enable it only when you know you do not have to
-	support such clients.  The default setting will change to `true`
-	at some stage, and setting this to `false` will continue to
-	prevent `git pack-refs` from being run from 'git-gc'.
+	Running `git pack-refs` in a repository renders it
+	unclonable by Git versions prior to 1.5.1.2 over dumb
+	transports such as HTTP.  This variable determines whether
+	'git gc' runs `git pack-refs`. This can be set to "nobare"
+	to enable it within all non-bare repos or it can be set to a
+	boolean value.  The default is `true`.
 
 gc.pruneexpire::
 	When 'git-gc' is run, it will call 'prune --expire 2.weeks.ago'.

base85.c

@@ -57,14 +57,8 @@ int decode_85(char *dst, const char *buffer, int len)
 		de = de85[ch];
 		if (--de < 0)
 			return error("invalid base85 alphabet %c", ch);
-		/*
-		 * Detect overflow.  The largest
-		 * 5-letter possible is "|NsC0" to
-		 * encode 0xffffffff, and "|NsC" gives
-		 * 0x03030303 at this point (i.e.
-		 * 0xffffffff = 0x03030303 * 85).
-		 */
-		if (0x03030303 < acc ||
+		/* Detect overflow. */
+		if (0xffffffff / 85 < acc ||
 		    0xffffffff - de < (acc *= 85))
 			return error("invalid base85 sequence %.5s", buffer-5);
 		acc += de;
@@ -84,8 +78,6 @@ int decode_85(char *dst, const char *buffer, int len)
 
 void encode_85(char *buf, const unsigned char *data, int bytes)
 {
-	prep_base85();
-
 	say("encode 85");
 	while (bytes) {
 		unsigned acc = 0;
@@ -118,7 +110,7 @@ int main(int ac, char **av)
 		int len = strlen(av[2]);
 		encode_85(buf, av[2], len);
 		if (len <= 26) len = len + 'A' - 1;
-		else len = len + 'a' - 26 + 1;
+		else len = len + 'a' - 26 - 1;
 		printf("encoded: %c%s\n", len, buf);
 		return 0;
 	}

builtin-checkout.c

@@ -397,7 +397,7 @@ static int merge_working_tree(struct checkout_opts *opts,
 		topts.initial_checkout = is_cache_unborn();
 		topts.update = 1;
 		topts.merge = 1;
-		topts.gently = opts->merge;
+		topts.gently = opts->merge && old->commit;
 		topts.verbose_update = !opts->quiet;
 		topts.fn = twoway_merge;
 		topts.dir = xcalloc(1, sizeof(*topts.dir));
@@ -422,7 +422,13 @@ static int merge_working_tree(struct checkout_opts *opts,
 			struct merge_options o;
 			if (!opts->merge)
 				return 1;
-			parse_commit(old->commit);
+
+			/*
+			 * Without old->commit, the below is the same as
+			 * the two-tree unpack we already tried and failed.
+			 */
+			if (!old->commit)
+				return 1;
 
 			/* Do more real merge */