base commit: r522257
diff --git a/Mk/Uses/python.mk b/Mk/Uses/python.mk
index 0d10c42bbb87..b080eedf15ac 100644
--- a/Mk/Uses/python.mk
+++ b/Mk/Uses/python.mk
@@ -323,40 +323,21 @@ _PYTHON_TEST_DEP=	yes
 .if ${PYTHON2_DEFAULT} != ${PYTHON_DEFAULT} && ${PYTHON3_DEFAULT} != ${PYTHON_DEFAULT}
 WARNING+=	"PYTHON_DEFAULT must be a version present in PYTHON2_DEFAULT or PYTHON3_DEFAULT, if you want more Python flavors, set BUILD_ALL_PYTHON_FLAVORS in your make.conf"
 .endif
 
 .if ${_PYTHON_ARGS} == "2"
 DEV_ERROR+=		"USES=python:2 is no longer supported, use USES=python:2.7"
 .elif ${_PYTHON_ARGS} == "3"
 DEV_ERROR+=		"USES=python:3 is no longer supported, use USES=python:3.5+ or an appropriate version range"
 .endif  # ${_PYTHON_ARGS} == "2"
 
-.if defined(PYTHON_VERSION)
-# A port/user requests a specific python version for its dependencies via
-# DEPENDS_ARGS, since it requires the specific python version itself.
-# Several things can happen now:
-#	a) the dependency supports the requested version -> everything's fine
-#	b) the dependency does not support the requested version
-#		1) the dependency works in a way that the different python
-#		   versions do not matter -> everything's fine
-#		2) the dependency is likely to break due to the conflict
-#		   nothing's fine
-#
-# b.2) needs to be resolved. Due to the complexity of how different pieces of
-# software are built, we can't solve this automatically. Instead, let's assume
-# that maintainers know what they are doing and assume PYTHON_VERSION to be a
-# hint. Just warn maintainers, if the versions do not match
-# (_PYTHON_VERSION_NONSUPPORTED).
-_PYTHON_VERSION:=	${PYTHON_VERSION:S/^python//}
-.else
 _PYTHON_VERSION:=	${PYTHON_DEFAULT}
-.endif # defined(PYTHON_VERSION)
 
 # Validate Python version whether it meets the version restriction.
 _PYTHON_VERSION_CHECK:=		${_PYTHON_ARGS:C/^([1-9]\.[0-9])$/\1-\1/}
 _PYTHON_VERSION_MINIMUM_TMP:=	${_PYTHON_VERSION_CHECK:C/([1-9]\.[0-9])[-+].*/\1/}
 _PYTHON_VERSION_MINIMUM:=	${_PYTHON_VERSION_MINIMUM_TMP:M[1-9].[0-9]}
 _PYTHON_VERSION_MAXIMUM_TMP:=	${_PYTHON_VERSION_CHECK:C/.*-([1-9]\.[0-9])/\1/}
 _PYTHON_VERSION_MAXIMUM:=	${_PYTHON_VERSION_MAXIMUM_TMP:M[1-9].[0-9]}
 
 # At this point we should have no argument left in ${_PYTHON_ARGS}
 # except a version spec
@@ -367,24 +348,20 @@ IGNORE=	uses unknown USES=python arguments: ${_PYTHON_ARGS}
 
 .undef _PYTHON_VERSION_NONSUPPORTED
 .if !empty(_PYTHON_VERSION_MINIMUM) && (${_PYTHON_VERSION} < ${_PYTHON_VERSION_MINIMUM})
 _PYTHON_VERSION_NONSUPPORTED=	${_PYTHON_VERSION_MINIMUM} at least
 .elif !empty(_PYTHON_VERSION_MAXIMUM) && (${_PYTHON_VERSION} > ${_PYTHON_VERSION_MAXIMUM})
 _PYTHON_VERSION_NONSUPPORTED=	${_PYTHON_VERSION_MAXIMUM} at most
 .endif
 
 # If we have an unsupported version of Python, try another.
 .if defined(_PYTHON_VERSION_NONSUPPORTED)
-.if defined(PYTHON_VERSION) || defined(PYTHON_CMD)
-_PV:=		${_PYTHON_VERSION}	# preserve the specified python version
-IGNORE=		needs Python ${_PYTHON_VERSION_NONSUPPORTED}, but ${_PV} was specified
-.endif # defined(PYTHON_VERSION) || defined(PYTHON_CMD)
 .undef _PYTHON_VERSION
 .for ver in ${PYTHON2_DEFAULT} ${PYTHON3_DEFAULT} ${_PYTHON_VERSIONS}
 __VER=		${ver}
 .if !defined(_PYTHON_VERSION) && \
 	!(!empty(_PYTHON_VERSION_MINIMUM) && ( \
 		${__VER} < ${_PYTHON_VERSION_MINIMUM})) && \
 	!(!empty(_PYTHON_VERSION_MAXIMUM) && ( \
 		${__VER} > ${_PYTHON_VERSION_MAXIMUM}))
 _PYTHON_VERSION=	${ver}
 .endif
@@ -447,39 +424,21 @@ PKGNAMESUFFIX=	${PYTHON_PKGNAMESUFFIX}
 .endif
 
 # To avoid having dependencies with @ and empty flavor:
 # _PYTHON_VERSION is either set by (first that matches):
 # - If using Python flavors, from the current Python flavor
 # - If using a version restriction (USES=python:3.5+), from the first
 #   acceptable default Python version.
 # - From PYTHON_DEFAULT
 PY_FLAVOR=	py${_PYTHON_VERSION:S/.//}
 
-# Pass PYTHON_VERSION down the dependency chain. This ensures that
-# port A -> B -> C all will use the same python version and do not
-# try to find a different one, if the passed version fits into
-# the supported version range.
-PYTHON_VERSION?=	python${_PYTHON_VERSION}
-.if !defined(PYTHON_NO_DEPENDS) && \
-    ${PYTHON_VERSION} != python${PYTHON_DEFAULT}
-DEPENDS_ARGS+=		PYTHON_VERSION=${PYTHON_VERSION}
-.endif
-
-# NOTE:
-#
-#  PYTHON_VERSION will hold whatever is passed down the dependency chain.
-#  If a user runs `make PYTHON_VERSION=python3.5, PYTHON_VERSION will be
-#  set to 'python3.5'. A port however may require a different version,
-#  which is stored (above) in _PYTHON_VERSION.
-#  Every python bit below hence should use python${_PYTHON_VERSION}, since
-#  this is the value, the _port_ requires
-#
+PYTHON_VERSION=	python${_PYTHON_VERSION}
 
 # Got the correct python version, set some publicly accessible variables
 PYTHON_VER=		${_PYTHON_VERSION}
 PYTHON_SUFFIX=		${_PYTHON_VERSION:S/.//g}
 PYTHON_MAJOR_VER=	${PYTHON_VER:R}
 PYTHON_REL=		# empty
 PYTHON_ABIVER=		# empty
 PYTHON_PORTSDIR=	${_PYTHON_RELPORTDIR}${PYTHON_SUFFIX}
 # Protect partial checkouts from Mk/Scripts/functions.sh:export_ports_env().
 .if !defined(_PORTS_ENV_CHECK) || exists(${PORTSDIR}/${PYTHON_PORTSDIR})
@@ -550,21 +509,21 @@ BUILD_DEPENDS+=	cython-${PYTHON_VER}:lang/cython@${PY_FLAVOR}
 RUN_DEPENDS+=	cython-${PYTHON_VER}:lang/cython@${PY_FLAVOR}
 .endif
 
 .if defined(_PYTHON_FEATURE_CONCURRENT)
 .if !defined(_PYTHON_FEATURE_FLAVORS) && (${_PYTHON_VERSION_MINIMUM:M3*} || ${_PYTHON_VERSION_MAXIMUM:M2*})
 DEV_WARNING+=	"USE_PYTHON=concurrent when only one of Python 2 or 3 is supported AND not using flavors does not make any sense"
 .endif
 _USES_POST+=		uniquefiles:dirs
 .if defined(_PYTHON_FEATURE_FLAVORS) && ${FLAVOR} == ${FLAVORS:[1]}
 UNIQUE_DEFAULT_LINKS=	yes
-.elif !defined(_PYTHON_FEATURE_FLAVORS) && ${PYTHON_VERSION} == python${PYTHON_DEFAULT}
+.elif !defined(_PYTHON_FEATURE_FLAVORS) && ${_PYTHON_VERSION} == ${PYTHON_DEFAULT}
 UNIQUE_DEFAULT_LINKS=	yes
 .else
 UNIQUE_DEFAULT_LINKS=	no
 .endif
 UNIQUE_PREFIX=		${PYTHON_PKGNAMEPREFIX}
 UNIQUE_SUFFIX=		-${PYTHON_VER}
 UNIQUE_SUFFIX_TYPES+=	SUFFIX_MAN
 UNIQUE_SUFFIX_MAN_WITH_EXT=	.[1-9ln]
 UNIQUE_SUFFIX_MAN_EXTRA_EXT=	.gz