contrib: Change 'remote' for personal branches and add branch creation script

Whilst trying to convert the add vendor branch script to work with
personal branches I encountered a minor issue where git would report
ambiguous refs when checking out the new branch.

It turns out that this is because git considers <me>/<topic> to be
ambiguous if both

  refs/heads/<me>/<topic>

and

  refs/remotes/<me>/<topic>

exist in the list of known branches.

Having thought about this a bit, I think the best solution is to adopt
something more like the vendors space and call the remote users/<me>
(this also works better if you want to set up remotes to track other
users branches as well).

So this patch has two parts.

1) It updates gcc-git-customization.sh to set up the new 'remote' and
converts any existing remote and branches tracking that to the new
format
2) It adds a new script to set up a personal branch on the gcc git repository.

	* gcc-git-customization.sh: Use users/<pfx> for the personal remote
	rather than just <pfx>.  Convert any existing personal branches to the
	new remote.
	* git-add-user-branch.sh: New file.

contrib/ChangeLog

@@ -1,3 +1,10 @@
+2020-01-24  Richard Earnshaw  <rearnsha@arm.com>
+
+	* gcc-git-customization.sh: Use users/<pfx> for the personal remote
+	rather than just <pfx>.  Convert existing personal branches to the
+	new remote.
+	* git-add-user-branch.sh: New file.
+
 2020-01-22  Richard Earnshaw  <rearnsha@arm.com>
 
 	* git-add-vendor-branch.sh: New file.

contrib/gcc-git-customization.sh

@@ -128,7 +128,7 @@ url=$(git config --get "remote.${upstream}.url")
 pushurl=$(git config --get "remote.${upstream}.pushurl")
 for v in $vendors
 do
-    echo "Migrating vendor $v to new remote vendors/$v"
+    echo "Migrating vendor \"$v\" to new remote \"vendors/$v\""
     git config --unset-all "remote.${upstream}.fetch" "refs/vendors/$v/"
     git config --unset-all "remote.${upstream}.push" "refs/vendors/$v/"
     git config "remote.vendors/${v}.url" "${url}"
@@ -140,15 +140,36 @@ do
     git config --add "remote.vendors/${v}.fetch" "+refs/vendors/$v/tags/*:refs/tags/vendors/${v}/*"
 done
 
-echo "Setting up tracking for personal namespace $remote_id in remotes/${new_pfx}"
-git config "remote.${new_pfx}.url" "${url}"
+# Convert the remote 'pfx' to users/pfx to avoid problems with ambiguous refs
+# on user branches
+old_remote=$(git config --get "remote.${old_pfx}.url")
+if [ -n "${old_remote}" ]
+then
+    echo "Migrating remote \"${old_pfx}\" to new remote \"users/${new_pfx}\""
+    # Create a dummy fetch rule that will cause the subsequent prune to remove the old remote refs.
+    git config --replace-all "remote.${old_pfx}.fetch" "+refs/empty/*:refs/remotes/${old_pfx}/*"
+    # Remove any remotes
+    git remote prune ${old_pfx}
+    git config --remove-section "remote.${old_pfx}"
+    for br in $(git branch --list "${old_pfx}/*")
+    do
+	old_remote=$(git config --get "branch.${br}.remote")
+	if [ "${old_remote}" = "${old_pfx}" ]
+	then
+	    git config "branch.${br}.remote" "users/${new_pfx}"
+	fi
+    done
+fi
+
+echo "Setting up tracking for personal namespace $remote_id in remotes/users/${new_pfx}"
+git config "remote.users/${new_pfx}.url" "${url}"
 if [ "x$pushurl" != "x" ]
 then
-    git config "remote.${new_pfx}.pushurl" "${pushurl}"
+    git config "remote.users/${new_pfx}.pushurl" "${pushurl}"
 fi
-git config --replace-all "remote.${new_pfx}.fetch" "+refs/users/${remote_id}/heads/*:refs/remotes/${new_pfx}/*" ":refs/remotes/${old_pfx}/"
-git config --replace-all "remote.${new_pfx}.fetch" "+refs/users/${remote_id}/tags/*:refs/tags/${new_pfx}/*" ":refs/tags/${old_pfx}/"
-git config --replace-all "remote.${new_pfx}.push" "refs/heads/${new_pfx}/*:refs/users/${remote_id}/heads/*" ":refs/users/${remote_id}"
+git config --replace-all "remote.users/${new_pfx}.fetch" "+refs/users/${remote_id}/heads/*:refs/remotes/users/${new_pfx}/*" "refs/users/${remote_id}/heads/"
+git config --replace-all "remote.users/${new_pfx}.fetch" "+refs/users/${remote_id}/tags/*:refs/tags/users/${new_pfx}/*" "refs/users/${remote_id}/tags/"
+git config --replace-all "remote.users/${new_pfx}.push" "refs/heads/${new_pfx}/*:refs/users/${remote_id}/heads/*" "refs/users/${remote_id}"
 
 if [ "$old_pfx" != "$new_pfx" -a "$old_pfx" != "${upstream}" ]
 then
@@ -157,3 +178,5 @@ fi
 
 git config --unset-all "remote.${upstream}.fetch" "refs/users/${remote_id}/"
 git config --unset-all "remote.${upstream}.push" "refs/users/${remote_id}/"
+
+git fetch "users/${new_pfx}"

contrib/git-add-user-branch.sh

@@ -0,0 +1,46 @@
+#! /bin/sh -e
+
+# Create a new upstream user branch.
+
+# Usage:
+#  contrib/git-add-user-branch.sh [<personal-prefix>/]<branch-name> <base>
+
+usage ()
+{
+    echo "Usage:"
+    echo "  $0 [<personal-prefix>/]<branch-name> <start-point>"
+    echo
+    echo "personal space must already have been set up using"
+    echo "contrib/gcc-git-customization.sh"
+    exit 1
+}
+
+if [ $# != 2 ]
+then
+    usage
+fi
+
+userpfx=$(git config --get "gcc-config.userpfx")
+user=$(git config --get "gcc-config.user")
+
+if [ -z "$userpfx" -o -z "$user" ]
+then
+    usage
+fi
+
+branch=$(echo "$1" | sed -r "s:(${userpfx}/)?(.*)$:\2:")
+start=$2
+
+# Sanity check the new branch argument.  If there is no '/', then the
+# vendor will be the same as the entire first argument.
+if [ -z "$branch" ]
+then
+    usage
+fi
+
+git push users/${userpfx} ${start}:refs/users/${user}/heads/${branch}
+git fetch -q users/${userpfx}
+git branch ${userpfx}/${branch} remotes/users/${userpfx}/${branch}
+echo "You are now ready to check out ${userpfx}/${branch}"
+echo "To push the branch upstream use:"
+echo "  git push users/${userpfx} ${userpfx}/${branch}"