nightlybuilds: switch to git.
Also specify branch to test to startnightly
nightlybuilds: use '-f' with 'git clean'
git change: update PETSC_VERSION_GIT in version.c [to be in sync with petscversion.h]
git change: update configure to remove auto-cloning of BuildSystem
git change: update configure to support 'git' detection and git 'clone' detection
nightlybuilds: update builddist to also take 'branch' as option.
If (branch=master) build petsc-dev.tar.gz else build petsc-BRANCHNAME.tar.gz
Also git clean need -d to remove dirs.
nightlybuilds - update git commands - and use 'petsc.clone' as reponame
nightlybuilds: also clean gitignores (build products)
Merge branch 'balay/nightlybuilds-change-to-git'

* balay/nightlybuilds-change-to-git:
  nightlybuilds: also clean gitignores (build products)
  nightlybuilds - update git commands - and use 'petsc.clone' as reponame
  nightlybuilds: update builddist to also take 'branch' as option. If (branch=master) build petsc-dev.tar.gz else build petsc-BRANCHNAME.tar.gz Also git clean need -d to remove dirs.
  git change: update configure to support 'git' detection and git 'clone' detection
  git change: update configure to remove auto-cloning of BuildSystem
  git change: update PETSC_VERSION_GIT in version.c [to be in sync with petscversion.h]
  nightlybuilds: use '-f' with 'git clean'
  nightlybuilds: switch to git. Also specify branch to test to startnightly
scalqpack.py install should make only lib not everything that a bare make makes
reason: bare make tries to make unneeded executables that cannot be built on some systems
Merge branch 'fix/scalapack-py-make-too-much/barry' into next
mat ex9.c: fix use of VecAXPY()
MatCompositeMerge: fix invalid access to scale after MatHeaderReplace()

We need scaling vectors to outlive destruction of the Mat_Composite.

Reported by Nachiket Gokhale <gokhalen@gmail.com> [petsc-maint #156279]
Merge branch 'jed/fix-mat-composite-merge-invalid-read' into next

* jed/fix-mat-composite-merge-invalid-read:
  MatCompositeMerge: fix invalid access to scale after MatHeaderReplace()
  mat ex9.c: fix use of VecAXPY()