Remove ability to change custom openssl path on upgrade #108

I reconsidered the feature that let users set or update a custom
openssl path using the --upgrade flag. This was unusual behaviour:
no other transcrypt settings could be altered during upgrade.

Since it is somewhat likely a user will need or want to change their
openssl path over a repository's lifetime, the help text now says
how to do that using a standard git config-setting command.

tests/test_init.bats

@@ -110,16 +110,16 @@ SETUP_SKIP_INIT_TRANSCRYPT=1
 }
 
 
-@test "init: transcrypt.openssl-path config setting is retained or updated with --upgrade" {
+@test "init: transcrypt.openssl-path config setting is retained with --upgrade" {
   init_transcrypt
   [[ "$(git config --get transcrypt.openssl-path)" = 'openssl' ]]
 
+  # Manually change openssl path
+  FULL_OPENSSL_PATH=$(which openssl)
+  git config transcrypt.openssl-path "$FULL_OPENSSL_PATH"
+
   # Retain transcrypt.openssl-path config setting on upgrade
   "$BATS_TEST_DIRNAME"/../transcrypt --upgrade --yes
-  [[ "$(git config --get transcrypt.openssl-path)" = 'openssl' ]]
-
-  # Replace transcrypt.openssl-path config setting if given on upgrade
-  FULL_OPENSSL_PATH=$(which openssl)
-  "$BATS_TEST_DIRNAME"/../transcrypt --upgrade --yes --openssl-path="$FULL_OPENSSL_PATH"
   [[ "$(git config --get transcrypt.openssl-path)" = "$FULL_OPENSSL_PATH" ]]
+  [[ ! "$(git config --get transcrypt.openssl-path)" = 'openssl' ]]
 }

transcrypt

@@ -725,10 +725,8 @@ upgrade_transcrypt() {
 	# Keep current cipher and password
 	cipher=$(git config --get --local transcrypt.cipher)
 	password=$(git config --get --local transcrypt.password)
-	# Keep current openssl-path, unless an explicit argument was given
-	if [[ ! $openssl_path_given ]]; then
-		openssl_path=$(git config --get --local transcrypt.openssl-path 2>/dev/null || printf "openssl")
-	fi
+	# Keep current openssl-path, or set to default if no existing value
+	openssl_path=$(git config --get --local transcrypt.openssl-path 2>/dev/null || printf '%s' "$openssl_path")
 
 	# Keep contents of .gitattributes
 	ORIG_GITATTRIBUTES=$(cat "$GIT_ATTRIBUTES")
@@ -880,6 +878,11 @@ help() {
 		            the password to derive the key from;
 		            defaults to 30 random base64 characters
 
+		     --openssl-path=PATH_TO_OPENSSL
+		            use OpenSSL at this path; defaults to 'openssl' in \$PATH.
+		            To change after initialization:
+		                git config transcrypt.openssl-path NEW_PATH
+
 		     -y, --yes
 		            assume yes and accept defaults for non-specified options
 
@@ -920,10 +923,6 @@ help() {
 		     -i, --import-gpg=FILE
 		            import the password and cipher from a gpg encrypted file
 
-		     --openssl-path=PATH_TO_OPENSSL
-		            use a specific openssl binary instead of the version in \$PATH.
-		            Use this with --upgrade to update transcrypt's openssl path
-
 		     -v, --version
 		            print the version information
 
@@ -986,7 +985,6 @@ show_file=''
 uninstall=''
 upgrade=''
 openssl_path='openssl'
-openssl_path_given=''
 
 # used to bypass certain safety checks
 requires_existing_config=''
@@ -1012,7 +1010,6 @@ while [[ "${1:-}" != '' ]]; do
 		;;
 	--openssl-path=*)
 		openssl_path=${1#*=}
-		openssl_path_given='true'
 		;;
 	-y | --yes)
 		interactive=''