Use modal CLI in trigger_copr

Hard-code COPR project names and switch them as well as prefix Release
tag based on mode.  This prevents from confusing builds.

trigger_copr

 }
 
 usage() {
-    warn "usage: $0 [options] COPR_PROJECT"
+    warn "usage: $0 [options] MODE"
     warn ""
     warn "Options:"
     warn ""
     warn "  -b BRN  build from branch BRN (default: last tag)"
+    warn "  -c COPR_PROJECT  COPR project name"
     warn "  -n      dry mode, don't do anything (just show"
     warn "          what would be done)"
     warn "  -r REL  use REL as Release number in SPEC file"
     warn "If -b is used, the project repo is temporarily clonded, and"
     warn "both Version and Release are found by consulting git-describe"
     warn "on the specified branch."
+    warn ""
+    warn "If MODE is 'scratch' (default), Release is pre-fixed by string"
+    warn "'0.scratch.' and build is triggered in scratch COPR project."
     exit 2
 }
 
     esac
 }
 
+choose_copr() {
+    #
+    # Choose COPR project based on $Mode
+    #
+    case $Mode in
+        scratch) echo amahdal/slop-scratch ;;
+        main)    echo amahdal/slop         ;;
+    esac
+}
+
+choose_relpfx() {
+    #
+    # Choose COPR project based on $Mode
+    #
+    test "$Mode" == scratch && echo 0.scratch.
+    return 0
+}
+
 main() {
     local Version       # Version in SPEC file
     local Release       # Release in SPEC file
     local Tmp           # our temp
     local Branch        # branch to use, if empty, tags are considered
     local DryRun=false  # do not do anything
+    local Mode=scratch  # implies COPR project and release prefix
     which copr >/dev/null \
      || die "copr not found, try 'sudo install copr-cli'"
     UrlBase=https://github.com/AloisMahdal/slop
     Tmp=$(mktemp -d)
     while true; do case $1 in
         -b) Branch=$2;      shift 2 || usage ;;
+        -c) CoprProject=$2; shift 2 || usage ;;
         -u) UrlBase=$2;     shift 2 || usage ;;
         -r) Release=$2;     shift 2 || usage ;;
         -v) Version=${2#v}; shift 2 || usage ;;
         -*) usage ;;
         *)  break ;;
     esac done
-    CoprProject=$1
-    test -n "$CoprProject" || usage
+    Mode=${1:-$Mode}
+    case $Mode in
+        main|scratch) : ;;
+        *)            usage ;;
+    esac
+    test -n "$CoprProject" || CoprProject=$(choose_copr)
     if test -n "$Branch"; then
         die "not implemented"
         test -n "$Version" || Version=$(git_guess ver)
         test -n "$Version" || Version=$(last_version)
         test -n "$Release" || Release=1
     fi
+    Release=$(choose_relpfx)$Release
     mkspec >"$Tmp/slop.spec"
     $DryRun && {
         warn "dry mode active, we would build:"