chore(tools): allow merging PR to whatever branch is checked out

Useful for either dev testing or merging PRs to dev branches. Also stop
updating local repo state beyond merging the PR.

MAINTAINING.md

@@ -58,7 +58,9 @@ git config --global alias.logs 'log --show-signature'
   merge-commit **must** be signed. To simplify the process, and ensure that
   things are done "right", it's preferable to use the [`merge-pr.sh`] script,
   which does that for you automatically.
-- **use** [`merge-pr.sh`] script to merge PRs, e.g. `./merge-pr.sh 1234`.
+- **use** [`merge-pr.sh`] script to merge PRs. First checkout the target
+  branch, usually either `master` or a release dev branch e.g. `v1.17-dev`,
+  make sure it's up to date with qTox/qTox, then e.g. `./merge-pr.sh 1234`.
 
   You don't have to use it, but then you're running into risk of breaking
   travis build of master & other PRs, since it verifies all commit messages,

merge-pr.sh

@@ -52,6 +52,9 @@ source_functions() {
 main() {
     local remote_name="upstream"
     local merge_branch="merge"
+    local base_branch # because assigning on the same line will break error code parsing.. http://www.tldp.org/LDP/abs/html/localvar.html
+    base_branch=$(git symbolic-ref HEAD --short)
+
     source_functions
     exit_if_not_pr $PR
     add_remote

tools/lib/PR_bash.source

@@ -60,24 +60,24 @@ add_remote() {
 after_merge_msg() {
     echo ""
     echo "PR #$PR was merged into «$@$PR» branch."
-    echo "To compare with master:"
+    echo "To compare with $base_branch:"
     echo ""
-    echo "  git diff master..$@$PR"
+    echo "  git diff $base_branch..$@$PR"
     echo ""
     if [[ "$@" == "merge" ]]
     then
-        echo "To push that to master on github:"
+        echo "To push that to $base_branch on github:"
         echo ""
-        echo "  git checkout master && git merge --ff $@$PR && git push upstream master"
+        echo "  git checkout $base_branch && git merge --ff $@$PR && git push upstream $base_branch"
         echo ""
-        echo "After pushing to master, delete branches:"
+        echo "After pushing to $base_branch, delete branches:"
         echo ""
         echo "  git branch -d {$@,}$PR"
         echo ""
     fi
     echo "To discard any changes:"
     echo ""
-    echo "  git checkout master && git branch -D {$@,}$PR"
+    echo "  git checkout $base_branch && git branch -D {$@,}$PR"
     echo ""
 }
 
@@ -88,7 +88,7 @@ after_merge_failure_msg() {
     echo ""
     echo "You may want to remove not merged branches, if they exist:"
     echo ""
-    echo "  git checkout master && git branch -D {$@,}$PR"
+    echo "  git checkout $base_branch && git branch -D {$@,}$PR"
     echo ""
 }
 
@@ -100,16 +100,13 @@ rm_obsolete_branch() {
 get_sources() {
     add_remote
     rm_obsolete_branch
-    git fetch $remote_name && \
-    git checkout master && \
-    git rebase $remote_name/master master && \
     git fetch $remote_name pull/$PR/head:$PR && \
-    git checkout master -b $merge_branch$PR
+    git checkout $base_branch -b $merge_branch$PR
 }
 
 # check whether to sign
 merge() {
     "${@}" --no-ff $PR -m "Merge pull request #$PR
 $OPT_MSG
-$(git shortlog master..$PR)"
+$(git shortlog $base_branch..$PR)"
 }