branch: lowercase error messages

Documentation/CodingGuidelines says “do not end error messages with a
full stop” and “do not capitalize the first word”.  Clean up existing
messages, some of which we will be touching in later steps in the
series, that deviate from these rules in this file, as a preparation for
the main part of the topic.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

branch.c

@@ -64,7 +64,7 @@ int install_branch_config(int flag, const char *local, const char *origin, const
 	if (skip_prefix(remote, "refs/heads/", &shortname)
 	    && !strcmp(local, shortname)
 	    && !origin) {
-		warning(_("Not setting branch %s as its own upstream."),
+		warning(_("not setting branch %s as its own upstream"),
 			local);
 		return 0;
 	}
@@ -116,7 +116,7 @@ int install_branch_config(int flag, const char *local, const char *origin, const
 
 out_err:
 	strbuf_release(&key);
-	error(_("Unable to write upstream branch configuration"));
+	error(_("unable to write upstream branch configuration"));
 
 	advise(_(tracking_advice),
 	       origin ? origin : "",
@@ -153,7 +153,7 @@ static void setup_tracking(const char *new_ref, const char *orig_ref,
 		}
 
 	if (tracking.matches > 1)
-		die(_("Not tracking: ambiguous information for ref %s"),
+		die(_("not tracking: ambiguous information for ref %s"),
 		    orig_ref);
 
 	if (install_branch_config(config_flags, new_ref, tracking.remote,
@@ -186,7 +186,7 @@ int read_branch_desc(struct strbuf *buf, const char *branch_name)
 int validate_branchname(const char *name, struct strbuf *ref)
 {
 	if (strbuf_check_branch_ref(ref, name))
-		die(_("'%s' is not a valid branch name."), name);
+		die(_("'%s' is not a valid branch name"), name);
 
 	return ref_exists(ref->buf);
 }
@@ -205,12 +205,12 @@ int validate_new_branchname(const char *name, struct strbuf *ref, int force)
 		return 0;
 
 	if (!force)
-		die(_("A branch named '%s' already exists."),
+		die(_("a branch named '%s' already exists"),
 		    ref->buf + strlen("refs/heads/"));
 
 	head = resolve_ref_unsafe("HEAD", 0, NULL, NULL);
 	if (!is_bare_repository() && head && !strcmp(head, ref->buf))
-		die(_("Cannot force update the current branch."));
+		die(_("cannot force update the current branch"));
 
 	return 1;
 }
@@ -230,7 +230,7 @@ static int validate_remote_tracking_branch(char *ref)
 }
 
 static const char upstream_not_branch[] =
-N_("Cannot setup tracking information; starting point '%s' is not a branch.");
+N_("cannot set up tracking information; starting point '%s' is not a branch");
 static const char upstream_missing[] =
 N_("the requested upstream branch '%s' does not exist");
 static const char upstream_advice[] =
@@ -278,7 +278,7 @@ void create_branch(struct repository *r,
 			}
 			die(_(upstream_missing), start_name);
 		}
-		die(_("Not a valid object name: '%s'."), start_name);
+		die(_("not a valid object name: '%s'"), start_name);
 	}
 
 	switch (dwim_ref(start_name, strlen(start_name), &oid, &real_ref, 0)) {
@@ -298,12 +298,12 @@ void create_branch(struct repository *r,
 		}
 		break;
 	default:
-		die(_("Ambiguous object name: '%s'."), start_name);
+		die(_("ambiguous object name: '%s'"), start_name);
 		break;
 	}
 
 	if ((commit = lookup_commit_reference(r, &oid)) == NULL)
-		die(_("Not a valid branch point: '%s'."), start_name);
+		die(_("not a valid branch point: '%s'"), start_name);
 	oidcpy(&oid, &commit->object.oid);
 
 	if (reflog)

t/t2018-checkout-branch.sh

@@ -148,7 +148,7 @@ test_expect_success 'checkout -b to an existing branch fails' '
 test_expect_success 'checkout -b to @{-1} fails with the right branch name' '
 	git checkout branch1 &&
 	git checkout branch2 &&
-	echo  >expect "fatal: A branch named '\''branch1'\'' already exists." &&
+	echo  >expect "fatal: a branch named '\''branch1'\'' already exists" &&
 	test_must_fail git checkout -b @{-1} 2>actual &&
 	test_cmp expect actual
 '

t/t3200-branch.sh

@@ -888,7 +888,7 @@ test_expect_success '--set-upstream-to fails on a missing src branch' '
 '
 
 test_expect_success '--set-upstream-to fails on a non-ref' '
-	echo "fatal: Cannot setup tracking information; starting point '"'"'HEAD^{}'"'"' is not a branch." >expect &&
+	echo "fatal: cannot set up tracking information; starting point '"'"'HEAD^{}'"'"' is not a branch" >expect &&
 	test_must_fail git branch --set-upstream-to HEAD^{} 2>err &&
 	test_cmp expect err
 '
@@ -975,7 +975,7 @@ test_expect_success 'disabled option --set-upstream fails' '
 test_expect_success '--set-upstream-to notices an error to set branch as own upstream' '
 	git branch --set-upstream-to refs/heads/my13 my13 2>actual &&
 	cat >expect <<-\EOF &&
-	warning: Not setting branch my13 as its own upstream.
+	warning: not setting branch my13 as its own upstream
 	EOF
 	test_expect_code 1 git config branch.my13.remote &&
 	test_expect_code 1 git config branch.my13.merge &&