create_branch: drop unused "head" parameter

This function used to have the caller pass in the current
value of HEAD, in order to make sure we didn't clobber HEAD.
In 55c4a6730, that logic moved to validate_new_branchname(),
which just resolves HEAD itself. The parameter to
create_branch is now unused.

Since we have to update and re-wrap the docstring describing
the parameters anyway, let's take this opportunity to break
it out into a list, which makes it easier to find the
parameters.

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

branch.c

@@ -228,8 +228,7 @@ N_("\n"
 "will track its remote counterpart, you may want to use\n"
 "\"git push -u\" to set the upstream config as you push.");
 
-void create_branch(const char *head,
-		   const char *name, const char *start_name,
+void create_branch(const char *name, const char *start_name,
 		   int force, int reflog, int clobber_head,
 		   int quiet, enum branch_track track)
 {

branch.h

@@ -4,15 +4,21 @@
 /* Functions for acting on the information about branches. */
 
 /*
- * Creates a new branch, where head is the branch currently checked
- * out, name is the new branch name, start_name is the name of the
- * existing branch that the new branch should start from, force
- * enables overwriting an existing (non-head) branch, reflog creates a
- * reflog for the branch, and track causes the new branch to be
- * configured to merge the remote branch that start_name is a tracking
- * branch for (if any).
+ * Creates a new branch, where:
+ *
+ *   - name is the new branch name
+ *
+ *   - start_name is the name of the existing branch that the new branch should
+ *     start from
+ *
+ *   - force enables overwriting an existing (non-head) branch
+ *
+ *   - reflog creates a reflog for the branch
+ *
+ *   - track causes the new branch to be configured to merge the remote branch
+ *     that start_name is a tracking branch for (if any).
  */
-void create_branch(const char *head, const char *name, const char *start_name,
+void create_branch(const char *name, const char *start_name,
 		   int force, int reflog,
 		   int clobber_head, int quiet, enum branch_track track);
 

builtin/branch.c

@@ -807,7 +807,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		 * create_branch takes care of setting up the tracking
 		 * info and making sure new_upstream is correct
 		 */
-		create_branch(head, branch->name, new_upstream, 0, 0, 0, quiet, BRANCH_TRACK_OVERRIDE);
+		create_branch(branch->name, new_upstream, 0, 0, 0, quiet, BRANCH_TRACK_OVERRIDE);
 	} else if (unset_upstream) {
 		struct branch *branch = branch_get(argv[0]);
 		struct strbuf buf = STRBUF_INIT;
@@ -853,7 +853,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		strbuf_release(&buf);
 
 		branch_existed = ref_exists(branch->refname);
-		create_branch(head, argv[0], (argc == 2) ? argv[1] : head,
+		create_branch(argv[0], (argc == 2) ? argv[1] : head,
 			      force, reflog, 0, quiet, track);
 
 		/*

builtin/checkout.c

@@ -628,7 +628,7 @@ static void update_refs_for_switch(const struct checkout_opts *opts,
 			}
 		}
 		else
-			create_branch(old->name, opts->new_branch, new->name,
+			create_branch(opts->new_branch, new->name,
 				      opts->new_branch_force ? 1 : 0,
 				      opts->new_branch_log,
 				      opts->new_branch_force ? 1 : 0,