vim-patch: Replace shell variables in printf with formatted args

This ensures that special characters in the variables are not
interpreted as escapes/format characters in the printf string, as was
seen with upstream patch 8.0.0615.

    $ ./scripts/vim-patch.sh -p 8.0.0615
    Updating Vim sources: /$HOME/src/neovim/.vim-src
    ✔ Updated Vim sources.
    ✔ Found Vim revision 'bf15b8d78b22661db8b19d662b62bb9a061cdd37'.
    Creating patch...
    Pre-processing patch...
    ✔ Saved patch to '/$HOME/src/neovim/vim-8.0.0615.patch'.

    Fetching 'origin/master'.
    ✔ From https://github.com/neovim/neovim
     * branch                master     -> FETCH_HEAD

    Creating new branch 'vim-8.0.0615' based on 'origin/master'.
    ✔ Switched to a new branch 'vim-8.0.0615'
    Branch 'vim-8.0.0615' set up to track remote branch 'master' from 'origin'.

    Creating empty commit with correct commit message.
    ./scripts/vim-patch.sh: line 40: printf: `w': invalid format character
    ✔ [vim-8.0.0615 db7fbb016] vim-patch:8.0.0615: using ./scripts/vim-patch.sh: line 44: printf: `w': invalid format character
    ✘ [vim-8.0.0615 db7fbb016] vim-patch:8.0.0615: using

[ci-skip]

scripts/vim-patch.sh

@@ -37,11 +37,11 @@ usage() {
 }
 
 msg_ok() {
-  printf "\e[32m✔\e[0m $@\n"
+  printf '\e[32m✔\e[0m %s\n' "$@"
 }
 
 msg_err() {
-  printf "\e[31m✘\e[0m $@\n"
+  printf '\e[31m✘\e[0m %s\n' "$@"
 }
 
 # Checks if a program is in the user's PATH, and is executable.
@@ -218,7 +218,7 @@ stage_patch() {
   local git_remote
   git_remote="$(find_git_remote)"
   local checked_out_branch
-  checked_out_branch="$(git rev-parse --abbrev-ref HEAD)"
+  checked_out_branch="$(git rev-parse --abbrev-ref HEAD)"
 
   if [[ "${checked_out_branch}" == ${BRANCH_PREFIX}* ]]; then
     msg_ok "Current branch '${checked_out_branch}' seems to be a vim-patch"
@@ -248,21 +248,22 @@ stage_patch() {
       printf "\n"
       msg_err "'patch' command not found\n"
     else
-      printf "\nApplying patch...\n"
+      printf "\nApplying patch...\n"
       patch -p1 < "${patch_file}" || true
       find -name '*.orig' -type f -delete
-    fi
+    fi
-    printf "\nInstructions:\n  Proceed to port the patch.\n"
+    printf "\nInstructions:\n  Proceed to port the patch.\n"
   else
-    printf "\nInstructions:\n  Proceed to port the patch.\n  Try the 'patch' command (or use '${BASENAME} -P ...' next time):\n    patch -p1 < ${patch_file}\n"
+    printf '\nInstructions:\n  Proceed to port the patch.\n  Try the "patch" command (or use "%s -P ..." next time):\n    patch -p1 < %s\n' "${BASENAME}" "${patch_file}"
-  fi
+  fi
 
   printf '
   Stage your changes ("git add ..."), then use "git commit --amend" to commit.
-
+
   To port more patches (if any) related to %s,
   run "%s" again.
-    * Do this only for _related_ patches (otherwise it increases the
+    * Do this only for _related_ patches (otherwise it increases the
+      size of the pull request, making it harder to review)
 
   When you are done, try "%s -s" to create the pull request.
 
@@ -398,24 +399,24 @@ show_vimpatches() {
 }
 
 # Prints a human-formatted list of Vim commits, with instructional messages.
-show_vimpatches() {
+show_vimpatches() {
   get_vim_sources
-  printf "\nVim patches missing from Neovim:\n"
+  printf "\nVim patches missing from Neovim:\n"
 
   list_missing_vimpatches | while read vim_commit; do
     if (cd "${VIM_SOURCE_DIR}" && git --no-pager  show --color=never --name-only "v${vim_commit}" 2>/dev/null) | grep -q ^runtime; then
-      printf "  • ${vim_commit} (+runtime)\n"
+      printf '  • %s (+runtime)\n' "${vim_commit}"
-    else
+    else
-      printf "  • ${vim_commit}\n"
+      printf '  • %s\n' "${vim_commit}"
-    fi
+    fi
-  done
+  done
-
+
-  echo
+  printf "Instructions:
-  echo "Instructions:"
+
-  echo
+  To port one of the above patches to Neovim, execute
-  echo "  To port one of the above patches to Neovim, execute"
+  this script with the patch revision as argument and
-  echo "  this script with the patch revision as argument and"
+  follow the instructions.
-  echo "  follow the instructions."
+
   Examples: '%s -p 7.4.487'
             '%s -p 1e8ebf870720e7b671f98f22d653009826304c4f'
 
@@ -436,7 +437,7 @@ review_commit() {
 
   echo
   if [[ -n "${vim_version}" ]]; then
-    msg_ok "Detected Vim patch '${vim_version}'."
+    msg_ok "Detected Vim patch '${vim_version}'."
   else
     msg_err "Could not detect the Vim patch number."
     echo "  This script assumes that the PR contains only commits"