Only support git 2.23 and above

When adding tests for all version I discovered that git before 2.23
caused subrepo issues due to how --is-ancestor worked. I tried to
find a way to support both versions, but was not successful so I
decided to drop support for the older versions.

Author: admorgan

Makefile

@@ -25,7 +25,7 @@ INSTALL_MAN1 ?= $(DESTDIR)$(PREFIX)/share/man/man1
 DOCKER_TAG ?= git-subrepo-testing:latest
 DOCKER_IMAGE := $(DOCKER_TAG)
 BASH_VERSIONS ?= 5.3 5.2 5.1 5.0 4.4 4.3 4.2 4.1 4.0 3.2
-GIT_VERSIONS := 2.51 2.48 2.40 2.30 2.29 2.25 2.17
+GIT_VERSIONS := 2.51 2.48 2.40 2.30 2.29 2.25 2.23
 
 # Create matrix of all bash/git combinations for comprehensive testing
 BASH_GIT_COMBINATIONS := $(foreach bash,$(BASH_VERSIONS),$(foreach git,$(GIT_VERSIONS),$(bash)-$(git)))

Meta

@@ -17,7 +17,7 @@ author:
 
 requires:
   bash: 4.0.0
-  git: 2.7.0
+  git: 2.23.0
 test:
   cmd: make test
 install: make install

ReadMe.pod

@@ -114,7 +114,7 @@ The best short answer is:
 
 The complete "Installation Instructions" can be found below.
 
-Note: git-subrepo needs a git version (> 2.7) that supports worktree:s.
+Note: git-subrepo needs a git version >= 2.23) due to changes in --is-ansestor.
 
 =head1 Commands
 

lib/git-subrepo

@@ -32,7 +32,7 @@ bash+:import :std can version-check
 
 VERSION=0.4.9
 REQUIRED_BASH_VERSION=4.0
-REQUIRED_GIT_VERSION=2.7.0
+REQUIRED_GIT_VERSION=2.23.0
 GIT_TMP=$(git rev-parse --git-common-dir 2> /dev/null || echo .git)/tmp
 
 # `git rev-parse` turns this into a getopt parser and a command usage message:

test/Dockerfile

@@ -131,17 +131,28 @@ RUN cd /root \
     && rm -fr bash* \
     && true
 
+# Buil/install bash-5.3
+RUN cd /root \
+    && wget https://ftp.gnu.org/gnu/bash/bash-5.3.tar.gz \
+    && tar -xzf bash-5.3.tar.gz \
+    && cd bash-5.3 \
+    && ./configure --prefix=/bash-5.3 \
+    && make \
+    && make install \
+    && rm -fr bash* \
+    && true
+
 
 # Build/install git-2.17
 RUN cd /root \
-    && wget --timeout=60 --retry-connrefused --tries=3 https://github.com/git/git/archive/v2.17.6.tar.gz \
-    && tar -xzf v2.17.6.tar.gz \
-    && cd git-2.17.6 \
+    && wget --timeout=60 --retry-connrefused --tries=3 https://github.com/git/git/archive/v2.23.4.tar.gz \
+    && tar -xzf v2.23.4.tar.gz \
+    && cd git-2.23.4 \
     && make configure \
-    && ./configure --prefix=/git-2.17 --with-openssl --with-libpcre --with-curl \
+    && ./configure --prefix=/git-2.23 --with-openssl --with-libpcre --with-curl \
     && make all -j$(nproc) \
     && make install \
-    && cd /root && rm -fr git* v2.17.6.tar.gz
+    && cd /root && rm -fr git* v2.23.4.tar.gz
 
 # Build/install git-2.25
 RUN cd /root \