pacman-helper quick_add: do handle symbolic links

When `MSYS` is set to `winsymlinks:nativestrict`, the MSYS2 runtime will
generate real Win32 symbolic links. This is something the `quick_add`
command did not expect, thinking that the `ln -s` command would generate
copies (which is the default of the MSYS2 runtime, believe it or not)
that can be overwritten. But it simply does not work because a symbolic
link cannot be overwritten with its target, not without removing the
link first.

This causes a problem since a recent `setup-git-for-windows-sdk` version
updated to a newer `@actions/toolkit` version that blatantly configures
the MSYS2 runtime to the `nativestrict` mode _for the entire remainder
of the workflow job_. For the full sadness of the details, see
actions/toolkit@2867e318d4d0de
(yes, it indeed has no adequate commit message).

Let's work around this issue by removing symbolic links, if any, before
copying the databases or their signatures to the suffix-less version.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

pacman-helper.sh

@@ -677,13 +677,23 @@ quick_add () { # <file>...
 		done
 		(cd "$dir/$arch" &&
 		 repo_add $sign_option git-for-windows.db.tar.xz $msys $mingw &&
-		 cp git-for-windows.db.tar.xz git-for-windows.db &&
-		 { test -z "$sign_option" || cp git-for-windows.db.tar.xz.sig git-for-windows.db.sig; } &&
+		 { test ! -h git-for-windows.db || rm git-for-windows.db; } &&
+		 cp git-for-windows.db.tar.xz git-for-windows.db && {
+			test -z "$sign_option" || {
+				{ test ! -h git-for-windows.db.sig || rm git-for-windows.db.sig; } &&
+				cp git-for-windows.db.tar.xz.sig git-for-windows.db.sig
+			}
+		 } &&
 		 if test -n "$db2"
 		 then
 			repo_add $sign_option git-for-windows-$db2.db.tar.xz $mingw &&
-			cp git-for-windows-$db2.db.tar.xz git-for-windows-$db2.db &&
-			{ test -z "$sign_option" || cp git-for-windows-$db2.db.tar.xz.sig git-for-windows-$db2.db.sig; }
+			{ test ! -h git-for-windows-$db2.db || rm git-for-windows-$db2.db; } &&
+			cp git-for-windows-$db2.db.tar.xz git-for-windows-$db2.db && {
+				test -z "$sign_option" || {
+					{ test ! -h git-for-windows-$db2.db.sig || rm git-for-windows-$db2.db.sig; } &&
+					cp git-for-windows-$db2.db.tar.xz.sig git-for-windows-$db2.db.sig
+				}
+			}
 		 fi) ||
 		die "Could not add $msys $mingw to db in $arch"
 	done